330 INVERTEBRATA OF MASSACHUSETTS. 



granulated but not hairy ; and its short, angular hand, and peculiar 

 thumb, which projects above into nearly a right angle, distinguish 

 it from all other species. 



P. LONGICA'RPUS. " Right hand larger and longer than the 

 left ; wrist and hand rather long, linear, and granulate ; fingers 

 short, white, equal." Say. 



Pagurus longicarpus, SAY ; Journ. Mead. Nat. Sc., i. 165. 



This is a very small species, inhabiting small specimens of 

 Buccinum, Natica, Purpura, &c. But it is easily distinguished 

 from the young of the two preceding species by its slender hand 

 and white fingers. 



GENUS HOMARUS. 



H. AMERICA'NUS. Rostrum two or three spined, with a smaller 

 one each side at base, one more distant on the thorax, and usually 

 one beneath near the tip ; wrist five spined above ; hand six or nine 

 spined on the inner edge. 



Antaeus marlnus Americanus, SEBA ; Thesaur., iii. pi. 17, f. 3. 

 Astacus marinus, LATR. ; SAY ; Journ. Mead. Nat. Sc., i. 165. 

 Homarus Americanus, MILNE-EDW.; Hist. Nat. des Crust., ii. 334. 



The common Lobster is too well known to require any com- 

 ments. It is found about all the islands along shore. 



GENUS ASTACUS, FABR. 



A. BARTO'NII. Rostrum concave, pointed; thorax unarmed; 

 hands short, destitute of spines ; fingers moderate. 



Astacus Bartonii, Bosc ; Hist, des Crust., ii. 62, pi. 2, f. 1. HARLAN; Med. and 



Phys. Researches, 230, fig. 3. SAY ; Journ. JLcad. Nat. Sc., i. 167. 

 Astacus affinis, MILNE-EDW. ; Hist. Nat. des Crust., ii. 332. 



The Craw-fish or Fresh-water Lobster is a miniature of the 

 common lobster, two inches or somewhat more in length. It is 

 strictly an inhabitant of fresh water, and more especially of moun- 

 tain streams, where it hides under stones, &c. It is much es- 

 teemed, as food, by many. The single, elongated point of the 



