58 
Guide to Crustacea. 
Tablc-casc The larvae of the Loricata are very unlike those of the related 
No. 11. groups, and are remarkable for their extremely flattened form and 
glassy transparency, and for the large size which they sometimes 
attain. They were formerly regarded as adult and independent 
species of Crustacea, and received the generic name of 
Phylldsoma (Fig. 37). 
Representatives of the extinct family Glyphaeidae are found 
fossil in rocks of Mesozoic age, from the Trias onwards. In some 
Fig. 37. 
The “ Phyllosoma ” larva of the common Spiny Lobster, much enlarged. 
(After J. T. Cunningham.) 
characters, such as the possession of a scale or exopodite on the 
antenna, and sometimes in having true chelae, they are much 
more primitive than the existing Loricata. A drawing of Glyphaea 
regleyana from the Jurassic of France is exhibited. 
In the Tribe Eryonidea the 'first four, and sometimes all five, 
pairs of legs are provided with chelae. Special interest attaches to 
this tribe on account of its geological antiquity. Fossil forms, not 
very different from those now living, are found in rocks of 
Mesozoic age, from the Trias onward. 
