12 



BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



idae (not included in this volume), in which the young issues from 

 the egg as a tiny crab substantially like its parent. 



Surprisingly little is known of the development of different species, 

 as the life history of not more than a dozen of our American species 

 of Brachyura has been worked out. This would prove a fruitful 

 field for investigators in our seaside laboratories where facilities 

 are offered for studying transformations in the aquarium. 



It is unwise to draw sweeping conclusions from a few cases, for 

 recently the discovery has been made of the direct development of the 

 young crab from the egg in a species of the Oxyrhyncha or spider- 

 crabs. 1 



ANALOGOUS SPECIES ON OPPOSITE SIDES OF THE CONTINENT. 



Throughout this volume, after the keys to species, I have indi- 

 cated in parallel columns those closely related species occurring on 

 opposite sides of the continent. The resemblance between the units 

 of some of these pairs is much greater than between others. All 

 are here assembled in a single list, followed by a list of those species 

 which occur on both sides of the continent ; those of world-wide range 

 being indicated by an asterisk (*). 



Family GONEPLACIDAE. 



Atlantic. 



Prionoplax atlantica. 

 Euryplax nitida. 

 Spcocarcinus carolinensis. 

 GJyptoplax smithii. 

 Chasmocarcinus typicus. 



Pacific. 



Prionoplax cilia ta. 

 Eiiri/plax polita. 

 Speocarcin us granulimanus. 

 Gll/ptoplax pugnax. 

 Chasmocarcinus latipes. 



Family PINNOTHERIDAE. 



Pinnotheres ostreum. 

 Falia byssomiac. 

 Para pin n ixa Jicndcrsoni. 

 Parapinnixa bouvicri. 

 Pinnixa brcripollcx. 

 Pinnixa faxoni. 

 Pinnixa cylindrica. 

 Pinnixa sayana. 

 Pinnixa floridana. 



Pinnotheres holmcsi. 

 Fabia canficldi. 

 Parapinnixa nitida. 

 Parapinnixa afflnis. 

 Pinnixa afflnis. 

 Pinnixa transvcrsalis. 

 Pinn ixa fra n cisca na. 

 Pinnixa occidcntalis. 

 Pinnixa longipes. 



Family CYMOPOLIIDAE. 



Cymopolia altcmata. 

 Cymopolia faxoni. 

 Cymopolia obcsa. 



CymopoUa zonata. 

 Cymopolia Jucasii. 

 Cymopolia tubcrculata. 



1 See Stalk-eyed Crustaceans collected at the Monte Bello Islands, 

 ban. Proc. Zool. Soc. London, 1914, pp. 053 and GG2. 



By Mary J. Kath- 



