ORDER DECAPODA — HOMARUS. 23 



This little Craw-fish, or Fresh-water Lobster, is exceedingly common in most of the 

 mountain streams of this and the adjoining States. It has been noticed by Bosc in Carolina, 

 and by Dr. Gould in Massachusetts. I am not aware of its extreme northern geographic 

 range. Their habits are nocturnal, concealing themselves during the day under stones. They 

 are rarely eaten, except by children in sport, although they are undoubtedly as palatable as 

 their European congener. The following species I have not seen, although it is said to be 

 found in the Delaware. I have searched for it without success in the tributaries of that 

 stream within the limits of this State. Milne-Edwards has made a singular transposition of 

 the names of these two species. 



(EXTRA-LIMITAL.) 



A. affinis. (Say, loc. cil. p. 168 and 443. Harlan, op. cit. p. 230, pi. fig. 3?) Rostrum mucronate, 

 subcanaliculate, two-spined ; a spine behind each eye, and a larger geminate one on each side of 

 the thorax; hand and thumb, on the inner edge, scabrous. Length, 3*3. River Delaware and 

 its tributaries. 



A- blandingii. (Harlan, loc. cit. p. 229, pi. fig. 1.) Rostrum mucronate, canaliculate, slightly 

 notched at the extremity ; a spine behind each eye. Arms tuberculated, elongated ; fingers slender, 

 unequal ; penultimate and antepenultimate legs of the male with an obtuse process at base of the 

 second joint. Length, 3-8. Marshes and Rivulets of the Southern States. 



A. oreganus. (Randall, Jour. Acad. Nat. Sc. Vol. 8, p. 138, pi. 7.) Body granulated; beak a long 

 slender spine, with a short spine on each side. Color, fuscous, with a large reddish spot on each 

 side posteriorly. Length. 4 • 0. Oregon Territory. 



GENUS HOMARUS. Edwards. 



Form of the preceding. Rostrum slender, narrow, and armed with many teeth on both sides. 

 Eyes spherical. Last ring of the thorax firmly united to the preceding. Hands exces- 

 sively developed. Medial caudal plate with lateral spines. Exclusively marine. 



HOMARUS AMERICANUS. 

 PLATE XII. FIGS. 52, 53. 



(STATE COLLECTION.) 



Aslacus marinus americanus. Seba, Thesaurus, Vol. 3, pi. 17, fig. 3. 



A. marinus. Say, Jour. Acad. Nat. Sciences, Vol. 1, p. 165. 



A. id. Milne-Edwards, Hist. Nat. des Crustacea, Vol. 2, p. 334. 



A. id. Gould, Invertebrata of Massachusetts, p. 330. 



Description. Rostrum narrow, acute, turned up at the tip, with two short spines at its base 

 and posterior to the eyes ; two or three spines on each side of the rostrum, followed by a 

 series of minute ones in large individuals ; one or two spines on the under side, near the tip ; 



