DEC A POD A. 



201 



ERYON, Desmar.^ 



All tin- leaflets of the caudal fin arc narrowed at their extremity 

 and tenninat" in a point; tlie external one presents no transverse 

 Miture. The two filaments of the mediate antennae are very short, 

 ami hardly longer than their peduncle. The sides of the shell are 

 dei-ply emarginatt-d. 



The forceps of the two anterior claws are narrow and elongated. 



This subgenus was established by Desmarest on a fossil species, 

 I, Hist. Nat. des Crust. FOSH., X, 4; Consid., XXXIV, 

 3, found in a lithographic, calcareous stone from Pappenheim and 

 Aichtedt in the margravate of Anspach. 



ASTACUS, Gronov.^ Fab. 



Leaflets of the lateral fins at the end of the tail widened and 

 rounded at their extremity; the external one divided transversely by 

 a suture, and the posterior extremity of the mediate obtuse, or rounded. 

 Tin- two li laments of the mediate antennae are much longer than 

 their peduncle. The sides of the shell are entire, or not incised. 



In >ome, all inhabiting salt water, the last segment of the tail, or 

 tint which occupies the middle of the terminal fin, presents no trans- 

 verse suture. 



Those whose lateral antennae have a large scale on their peduncle, 

 whose eyes are very large and reniform, and the forceps of whose 

 two anterior claws are narrow, elongated, prismatic, and equal, 

 form the genus NEPHROPS of Leach, the type of which is the Cancer 

 norwegicut, L. ; de Geer, Insect., VII, XXI; Herbst., XXVI, 3; 

 I , ich, Malac. Brit., XXVI. The two anterior claws are furnished 

 with dent.ited spines and ridges, and the superior surface of the tail is 

 sculptured. It is found in the seas of the north of Europe, and in the 

 Mediterranean. 



Tli<iM in which the peduncle of the lateral antennae presents no- 

 thing but two short projections in the form of teeth or spines, whose 

 eyes are neither large nor reniform, and whose forceps are more or 

 less oval, compose, with the fresh water species, the genus Aflacus, 

 properly so called, of the same author. 



Aitacus ma/imty, Fab.; Cancer (jammarus, L. ; Herbst., 

 XXV; IVnn., llrit. Xo..l.,V.x. 21; (the Common Lobster). The 

 point or rostrum of the anterior extremity of the shell h;ts three 

 teeth on each >ide, and another double one at its base. The an- 

 terior (laws are very large and unequal ; the largest finger of the 

 forceps is oval, with great molar teeth, the other is elongated, 

 and Ins num-TiMi- Mnall ones. Old individuals are sometimes 

 more than half a metre in length. Its flesh is highly esteemed. 

 It is found in the European Ocean, in the Mediterranean, an I 

 even on th- coasts of North America. Its internal 



structure has been carefully studied by Messrs. Victor And 

 and Mi yds. 



In the fresh wat >r species, which otherwise resemble the preced- 

 ing in their antenna, eyes, and form of the claws, the last be^nvnt of 



