564 



CRUSTACEA. 



such as Pe?2ceus and sEger ; the Spiny Lobsters (Palinuridce) are 

 exemplified by the singular Mecochirus (fig. 426) of the Solenhofen 

 Slates, in which the first pair of ambulatory limbs are enormously 



elongated, but do not terminate in 

 pincers ; the Glyfthceidce are repre- 

 sented by Glyphcea itself, and the 

 genus Pseudastacus takes the place of 

 the modern Lobsters. The most re- 

 markable group of the Jurassic Mac- 

 rura is, however, that of the Eryonidce, 

 of which the principal genus is Eryon 

 itself. This interesting family has rep- 

 resentatives in the Trias, and is very 

 widely distributed in the Jurassic and 

 Cretaceous rocks, while recent investi- 

 gations have shown that a few forms of 

 the group (such as Wilkmoesid) still 

 maintain their existence at the bottom 

 of the deep sea. In Eryon (fig. 427), 

 the carapace is large and broad, and 

 nearly quadrate in figure, whilst the 

 antennae are very small ; the first four 

 pairs of ambulatory legs are chelate, and the first pair are much 

 longer than the others ; and the caudal extremity is constituted by 

 the triangular telson and the dilated last pair of swimmerets. Beau- 

 tifully preserved examples of Eryon are found in the Lithographic 



Fig. 425. — A nthrafialcemon gracilis, 

 of the natural size. From the Coal- 

 measures of North America. (After 

 Meek and Worthen.) 



Fig. 426. — Mecochirus longimanus, from the Lithographic Slates of Eichstadt, 

 one-half the natural size. (After Zittel.) 



Slates of Germany, and in the same deposits are found the remains 

 of " Phyllosomae," which are to be regarded as the larval stages of 

 the former. In the Cretaceous jocks, Macrurous Decapods are 

 tolerably numerous, and belong to all the principal sections of the 



