AETHEOPODA — CEUSTACSA. 



99 



outer covering they are not common as fossils. Uclorella Gallery 



of the Cretaceous of Lebanon is probably an ancestral -^^J'^'^g^ 



form derived from the Penaeidae. The common British 12c. 



prawn and the river-prawns of the tropics belong to a 



family Palaemonidae. Some fossils of this family found Table-case 



in the Oligocene Osborne Beds of the Isle of Wight are 20. 



exhibited. 



Among the more conspicuous crustaceans in the Liassic Table-case 

 rocks of England is the genus Eryon, of which the first 21. 

 representatives occur in the foreign Trias. These are the 

 earliest examples of the still extant tribe Eryonidea, in 

 which the first four pairs, and sometimes all five pairs, of 

 legs bear pincer-claws. The existing genera are mainly 

 confined to the deep sea, and, like many other deep-sea 

 animals, are blind. It is, however, plain that the fossil 

 Eryon lived in much shallower waters. The genus is found 

 also in the Solenhofen Stone, which was apparently deposited Wall-case 

 in a lagoon (Fig. 46, 5). Its latest species is of N'eo- 13a. 

 comian age. 



Next we notice the many fossils of GlyjpJiaea (Fig. 45) Table-case 

 representing the extinct family Glyphaeidse. These are of 

 much interest as the ancestors of all the recent Loricata, a 

 tribe represented in modern seas by the Palinuridae and 

 Scyllaridae. The Palinuridse are familiar through the rock- 

 lobster, the langouste of the French (Palinurus mUgaris) ; 

 the body is more or less cylindrical, and the antennae are 

 long, cylindrical, and jointed. In the Scyllaridae the body is 

 flattened, and the antennae are expanded into broad plates, 

 which are said to be used as shovels in burrowing. All 

 these lobster-like forms may be distinguished from true 

 lobsters by the absence of pincer-claws, though in the female 

 the last pair of legs has them imperfectly developed. Now 

 the Glyphaeidae have antennae still of primitive form, with a 

 stalk of many segments none of which are joined to the 

 upper lip-plate as they are in recent Loricata, and with a 

 feeler-portion only moderately developed ; the legs have no 

 regular pincer-claws, but there is a tendency towards their 

 formation in the first pair, which is larger than the rest ; 

 they all have a small pointed rostrum. Along with Glyijliaea Table-ease, 

 we find Scapheus and Preatya in the Lower Lias of England. 

 These were preceded by Pcmphix, of which there are Wall-case 

 specimens from the foreign Trias, and were followed by l^-^- 

 Pseudoglyphaea in Liassic and Oolitic rocks, by the long- 

 limbed Mecochirus of Oxfordian and Kimmeridsrian ao-e 



H 2 



