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 ; lorist and hand rather long, linear, and granulate ; fingers 

 short, ivhite, equal.'''' Say. 



Pagurus longicarpus, Say ; Journ. Acad. JVat. 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 tioo 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. 



Astacus marinus Americ^nus, Seba ; Thesaur., iii. pi. 17, f. 3. 

 Astacus marinus, Latr. ; Say ; Journ. Jicad. 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. Acad. Nat. Sc, 1. 167. 

 Astacus affinis, Milne-Edw. ; Hist. A''at. 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 



