VII. CONTRIBUTIONS FROM THE ZOOLOGICAL LABORATORY No. VII. DESCRIPTIONS OF NEW SPECIES OF CAMBARUS; TO WHICH IS ADDED A SYNONYMICAL LIST OF THE KNOWN SPECIES OF CAMBARUS AND ASTACUS. By WALTER FAXON. Communicated November 12th, 1884. SIXTEEN years have elapsed since the North American Crayfishes were revised by Dr. Hagen.* In the mean while a large amount of new material has accumulated in the Museum of Comparative Zoology. On examination, this material revealed so many new forms, and shed so much light on the variability and geographical distribution of these animals, that it seemed desirable to subject the group anew to a critical revision. With this in view I have examined all the collections accessible, including those belonging to the Museum of Comparative Zoology, the Boston Society of Natural History, the Peabody Academy of Science at Salem, Mass., the Academy of Natural Sciences of Philadelphia, the United States National Museum at Washington, D. C., Yale College, New Haven, Conn., Bowdoin College, Brunswick, Me., and Butler University, Irvington, Ind., together with the private collections of Mr. P. R. Uhler of Baltimore, Md., Prof. O. P. Hay of Irvington, Ind., Prof. L. A. Lee of Brunswick, Me., Prof. A. S. Packard of Providence, R. I., Prof. D. S. Jordan of Washington, D. C., Mr. R. S. Tarr of Gloucester, Mass., Dr. C. Hart Merriam of Locust Grove, N. Y., and Prof. B. F. Koons of Mansfield, Conn. Only through the kind offices of the curators of these collections was a thorough revision of this difficult group possible. I have now ready for the press the first part of a revision of the Astacina, embracing * Ill. Cat. Mus. Comp. Zool., No. III. This monograph was finished in 1868, although not published until 1870. all the Crayfishes found in the Northern hemisphere, viz. the family Potamobiida of Huxley. Owing to unavoidable delay in the publication of the full Revision in the Memoirs of the Museum of Comparative Zoology, illustrated by quarto lithographic plates, it is thought advisable to publish the following descriptions of the new species. All of them will be figured in the final Memoir. GENUS CAMBARUS. § 1. Third and fourth pairs of legs of male furnished with hooks on the third segment. First abdominal appendages of the male with outer part truncate at the tip and furnished with one to three small recurved teeth, inner part ending in an acute spine which is generally directed outwards. Male, form I. a. Rostrum with ante-apical lateral spines. 1. C. HAYI, sp. nov. Rostrum broad, triangular, excavated, sparsely pubescent above, acumen short, lateral spines moderate. Carapace punctate above, granulated on the sides, the granules ciliate. Lateral spines slightly developed in fully-grown individuals, more prominent in the young. Areola narrow. Abdomen broad, shorter than the cephalo-thorax. Pleural angles rounded. Proximal segment of telson with two spines on each side of the distal border. Hind margin of telson slightly coucave. Anterior process of epistoma broadly triangular. Antennæ shorter than the body. Antennal scale a little shorter than the peduncle, equal to the rostrum, broad, broadest at the middle. Chelipeds slender, chela long, inner and outer margins parallel, squamoso-tuberculate, tubercles ciliate, those along the inner margin of the hand blunt spiniform. Fingers longer than the hand. Opposed margins of fingers ciliate, with one or two small spinous teeth. Carpus long triangular, smooth without, tuberculate and spinous within. Meros with scattered puncta without, tuberculate on the upper margin, one or two spines at the anterior end of upper margin, two rows of spines beneath. Third and fourth pairs of legs hooked on third segments. Anterior abdominal legs of moderate length, deeply excavated on the outer side near the tip. A beardlike tuft of cilia from the protuberance behind the excavation. Tip bears three flattened horny teeth. Inner part ciliate, with a long spine directed outwards and forwards. The second form of the male has shorter chelipeds, smaller hooks |