latum, segmento antico paulo oblongo, angulis posticis truncatis et setam minutam gerentibus, segmento postico brevi, ano prominente; stylis parvulis, triangulatis, ad angulos insitis, anum non superantibus, setis tribus, plumosis.

Hab. in corpus Squali, mari Pacifico prope Novi-Zealandiam. Lect. die 15 Ap., 1840.

Genus III. PANDARUS. (Leach.)

Cephalothorax 4-articulatus, carapace grandi, segmentis sequentibus transversis, secundo ad latera alatè producto, tertio quartoque posticè alatis, et bilobatis. Abdomen 2-3-articulatum, segmento ultimo tecto, secundo posticè rotundato et utrinque stylis caudalibus sæpius munito. Pedes paris secundi crassè cheliformes; natatorii octo, setis brevissimis. Oculi duo, remotiusculi. Oculi duo, remotiusculi. Styli caudales stylifor

mes, acuti, subnudi.

1. PANDARUS CONCINNUS. - Carapax paulo oblongus, ellipticus, posticè truncatus et dentatus, angulis posticis paululo elongatis, obtusis. Segmentum secundum brevissimum, alis divaricatis, subrectangulatis, angulis posticis subacutis. Segmenta duo sequentia transversa, subæqua, lobis rotundatis acutè sejunctis. Abdomen 3-articulatum, segmento antico lato, postice profundè excavato, lateribus arcuatis, angulis posticis acutis, bene divaricatis. Styli caudales non tecti.

Hab. in corpus Squali, mari Pacifico juxta insulam "Tongatabu."

2. PANDARUS SATYRUS. — Carapax vix oblongus, posticè sensim latior, angulis posticis parce prominentibus, margine postico integro, antico obsoletè denticulato. Segmentum secundum brevissimum, alis divaricatis, oblongo-ellipticis. Segmenta cephalothoracis sequentia transversa, primo minore, lobis rotundatis acutè sejunctis. Abdomen 3-articulatum, articulo antico grandi, posticè angusto-excavato, lateribus fere rectis, parce deinde subito angustioribus et angulis posticis internis. acutis; segmento secundo dimidio vix angustiore, oblongo, obovato. Styli caudales non tecti.

Long. 5". Hab. in corpus Squali, mari Pacifico juxta insulam "Tongatabu."

3. PANDARUS BREVICAUDUS. Carapax vix oblongus, subellipticus, posticè valde excavatus, angulis posticis longè productis, obtusis. Segmenta sequentia tria transversa. Alæ segmenti secundi non divaricatæ, posticè obtusa. Segmenta tertium quartumque abdomine non latiora,

margine dorsali postico latè excavato. Segmentum abdominis anticum subquadratum, angulis posticis obliquè truncatis et setâ minutâ extus instructis, posticè angustum, subtruncatum; segmentum secundum parvulum, transversum stylis triplo longioribus.

Long. ". Hab. in corpus Squali, mari Pacifico prope Novi-Zealandiam.

Genus IV. DINEMATURA. (Latreille.)

Cephalothorax 3-articulatus, segmento secundo parvo, testâ tertii dorsali posticè valde expansâ et profundè bilobatâ, eoque elytroideâ. Abdomen 2-articulatum, carapace paulo angustius, oblongus, segmento antico maximo, posticè bilobato, postico parvulo, celato. Styli caudales lamellati, terminales.

DINEMATURA BRACCATA. - Carapax fere rotundatus, abdomine latior, discis suctatoriis post antennas munitus; posticè quadrilobatus, lobis duobus internis angustis, curvatis, subacutis. Segmentum secundum transversum, ad latus subacutum. Segmenti alæ tertii vix oblongæ, dimidii abdominis longitudine, posticè parce latiores, angulis rotundatis, margine postico fere recto. Segmentum abdominis primum profundè bilobatum, secundum quadratum. Styli caudales grandes, subovati, abdominis extremitatem paulo superantes, setis paucis brevissimis.

Long.". Hab. in corpus Squali, mari Pacifico juxta insulam "Tongatabu."

Genus V. LEPIDOPUS. (Dana.)

Corpus anticè non latius. Cephalothorax 3-articulatus, carapace minore quam abdomen, segmentis duobus sequentibus posticè largè bialatis. Abdomen 2-articulatum, segmento postico parvulo, celato, antico maximo et posticè bilobato. Antenna postica articulo tenui falciformi confectæ. Pedes paris secundi superficie terminali latâ prehensili squamatâ instructi. Pedes natatorii quatuor ultimi similes, latè lamellati.

LEPIDOPUS ARMATUS. — Corpus oblongum, posticè sensim latius. Carapax subquadratus, posticè paulo latior, margine postico vix arcuato. Segmenta duo sequentia subæqua, alis grandibus, fere rotundatis. Abdomen oblongum, carapace valde longius, postiĉè non angustius, paulo bilobatum, lobis rotundatis. Antennæ posticæ ad apicem longè falciformes et denticulis biseriatis armatæ, articulo penultimo subquadrato.

Pedes paris secundi grandes, articulo penultimo ad apicem spinigero, ultimo crassissimo, superficie terminali oblongâ, squamatâ, squamulis spinulâ armatis.

Long. ".- Hab. in corpus speciei Musteli (Squalorum familiæ). –

- Lect. ad urbem "Rio de Janeiro."

Tribus 4. NYMPHACEA.

Genus ASTRIDIUM. (Dana.)

Pycnogono affinis. Caput duobus maxillipedibus subtus instructum parvulis, debilibus, apice obtusis, non prehensilibus. Pedes octo unguiculo confecti. Abdomen perbrevis.

ASTRIDIUM ORIENTALE. - Cephalothorax stellatus, segmentis medio connatis, deinde liberis. Abdomen breve, posticè angustius, obtusum. Truncus buccalis oblongus, subcylindricus, corpore vix brevior. Segmentum corporis primum anticè non transversum, posticè angustius et deinde utrinque longè productum instar rami brevis,* et pedes anticos gerens. Maxillipedes parvuli, obsoletè 3-articulati, obtusi. Pedes crassiusculi, articulo primo vix oblongo, sequentibus sex subæquis, tertio paulo breviore.

Long. ". - Hab. in mari "Sulu." Lect. die 11 Feb., 1842.

Mr. Borden, from the committee to whom was referred the paper of Mr. M. Conant, describing his "Solar Index," presented a report, entering fully into the investigation of the principles of the instrument. The conclusion which the committee has arrived at is, that, although the "Solar Index" is not susceptible of sufficient accuracy to be used with advantage for nice scientific purposes, yet, as it can be managed with great facility, it may frequently be found valuable to the surveyor and engineer in making experimental surveys, running preliminary lines, &c., for the purpose of learning the character of the topography of a country, and of acquiring, approximately at least, a knowledge of the relative situation of places.

* Hæc pars postica segmenti primi segmentum corporis secundum vere est, quamvis articulatione verâ non sejuncta.

Professor Horsford presented the following communication, embodying the results of his investigations and experiments on the chemical action of water of various kinds upon the materials ordinarily employed for its transmission and distribution.

"Materials for the transmission of water, to be used as a beverage in any form, should be strong and durable, should admit of ready repair and replacement, be sufficiently cheap to permit general use, and, above all, should impart no deleterious property to the waters served through them. The safety of using water supplied through wooden aqueducts, and the certainty of their rapid decay, are too well known to require more particular mention. Pipes of iron, tin, of tinned iron, tinned copper, tinned lead, glass, and gutta percha, are of comparatively recent introduction. They are believed, so far as experience has shown, to impart few or no deleterious properties to water as a beverage, though all of them are wanting in some of the essential attributes just mentioned.

"As pipes of lead have been long in use, and possess in an eminent degree most of the properties required for aqueduct service, and as the following researches have been more especially directed to ascertain the true value of leaden pipes for the distribution of water, a brief historical sketch of the opinions that have been entertained with regard to the safety of employing them may not be without interest.

"The period of the first employment of lead for transmitting water is unknown; but the fact that it was condemned by Vitruvius, a Roman architect believed to have lived about nineteen hundred years ago, is evidence of its having at that time been long enough in use to furnish the experience which led to its rejection as a material for aqueducts.* Galen, a physician of Amsterdam, who wrote in the seventeenth century, coincided with Vitruvius. Both had observed the formation of white lead in water-pipes, and attributed to it the illness which was known to affect those who drank certain waters served through leaden pipes. Notwithstanding these strongly expressed opinions and occasional fatal consequences from drinking water containing lead in solu

* Leaden pipes may be seen at this day among the ruins of the Coliseum, and leading to the baths and fountains of Herculaneum and Pompeii.

Kopp thinks lead as a metal was known to the Israelites. Geschichte der Chemie. It is certain that it was known and in use 400 years before the Christian era.

tion, public sentiment continued strongly in favor of this kind of pipes; and until about the commencement of the present century no experimental examination of the subject had been undertaken. Dr. Lamb of England, and later Guyton Morveau of France, devoted their attention for a time to this inquiry. Their opinions illustrate the uncertainty which attends the earlier labors in every field of investigation. The one believed that most, if not all, spring waters possess the property of acting upon lead to such an extent as to render their conveyance through leaden tubes unsafe, and this because of the salts in solution;

the other, that many natural waters scarcely act on lead at all, and because of the salts in solution. The former believed that rain or snow water (eminently pure) does not corrode lead; the latter, that distilled water, the purest of all waters, acts rapidly on it. Dr. Thompson of Glasgow subsequently gave some consideration to the subject, and came to the conclusion, that, though Dr. Lamb's general proposition was true, the lead was not dissolved, but suspended merely. Such was the doubt upon this point, the insolubility of oxide of lead, — that a scientific association in Germany made it a prize problem. The honor of deciding the question was accredited to Brendecke, whose views were coincided in by his unsuccessful competitor, Siebold,* and also by Herberger, who prepared his oxide of lead in a different manner, and reported his results at a later period. They decided that oxide of lead is insoluble in water.

"The imperfection of the investigation and the injustice of this award have since been established by the labors of Yorke, † and Bonsdorff, who have found that aerated, distilled water, deprived of carbonic acid, oxidates metallic lead and dissolves the oxide in the proportion of from 7both to Tooth. Even the acute Scheele had remarked the same fact in the last century. Philips denied the accuracy of the conclusions of both Yorke and Bonsdorff, and maintained, with Thompson, that the oxide of lead was not soluble, but was only in suspension. His view was supported by the fact, that filtration seemed to separate the lead from the water that originally contained it. In 1846 Yorke § reviewed the investigation of Philips, and showed that, in filtration, the oxide of lead enters into combination with the woody fibre of the filter

*

Phar. Cent. Blatt., 1835, p. 831; Buch. Rep., III., pp. 155 – 179.

Pogg. Ann., XXXIII., pp. 110-112.

Phar. Cent. Blatt., 1836, p. 520; Buch. Rep., V., pp. 55-59.