No. 462.] CRABS OF GAY HEAD MIOCENE. 387 
a very different sternum, abdomen, and outer maxilliped from 
that shown in the specimen under discussion. This species rep- 
resented by the male specimen and the hand originally described, 
and now by this cast of the under side of a female, shows that 
it must have been far less common than the Archzeoplax. 
Further search, however, should yield more specimens of this 
species. I am greatly indebted to Dr. Walter Faxon of the 
Museum of Comparative Zoólogy for help in placing this speci- 
men in its present position, for although its condition would not 
give its complete relations there was nothing to preclude its 
being a Cancer. 
Many of the Archzoplax had specimens of Balanus concavus 
Bronn attached to the carapace, as has been already noted in a 
previous paper. 
Boston SOCIETY OF NATURAL HISTORY, 
March, 1905. 
