ARTHROPODA— CRUSTACEA. 
99 
outer covering they are not common as fossils. UdorcUa 
of the Cretaceous of Lebanon is probably an ancestral 
form derived from the I’enaeidae. The common British 
prawn and the river-prawns of the tropics belong to a 
family Palaemonidae. Some fossils of this family found 
in the Oligocene Osborne Beds of the Isle of Wight are 
exhibited. 
Among the more conspicuous crustaceans in the Liassic 
rocks of England is the genus Eryon, of which the first 
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 
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 
in a lagoon (Fig. 46, 3). Its latest species is of ISTeo- 
cornian age. 
Next we notice the many fo.ssils of Glypliaca (Fig. 45) 
representing the extinct family Glyphaeidre. These are of 
much interest as the ancestors of all the rticeut Loricata, a 
tribe represented in modern seas by the Palinuridm and 
Scyllarhlfe. The Paliuuridm are familiar through the rock- 
lobster, the langouste of the French (Palimirus vidyaris) ; 
the body is more or less cylindrical, and the antennae are 
long, cylindrical, and jointed. In the Scyllaridae the body is 
flattened, and the antennai are expanded into broad plates, 
which are said to be used as shovels iu burrowing. All 
these lobster-like forms may be distingui.shed from true 
lobsters by the absence of pincer-claws, though in the female 
the last pair of legs has them imperfectly developed. Now- 
the Glyphaeidte have antenme still of primitive form, with a 
stalk of many segments none of which are joined to the 
upper lip-])late as they are iu recent Loricata, and with a 
feeler-portion only moilerately 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 ])ointed rostrum. Along with Glyphaca 
we find Scaphms and Prcalya in the Lower Lias of England. 
These were j^receded by Pcmphix, of which there are 
specimens frmn the foreign Trias, and were followed by 
I’seudoylyphaca in Liassic and Oolitic rocks, by the lomr- 
limbed Mecochiriis of Oxfordian and Kimmeridgian a«e 
Qallery 
VIII. 
Wall-caje 
12c. 
Table-case 
20 . 
Table-ease 
21 . 
Wall-ease 
13A. 
Table-case 
21 . 
Table-case 
21 . 
Wall-case 
13 a. 
