153 



a commensalistic mode of living with Lamellibranchs, in worm-tubes, corals etc. is either proved 

 or rêndered most likelj'. 



The monoorapher's task is greatly impaired by a large number of species, and even of 

 not a few o-enera, being very incompletely known and especially by the scarcity of good figures. 

 Alcock indeed has given a most useful synopsis of British Indian species; he distinguishes the 

 followino- subfamilies: Pseudorhombilinae, Goneplacinae^ Prionoplacinac, Rhizopinae and Hexa- 

 podinae. Miss Rathbux ') has afterwards proposed a new subfamily, TypJdocarcinopsinae, which 

 for reasons explained further on I have not maintained. 



The discrimination of the subfamilies has been given by Alcock. 



Subfam. Pseudorhombilinae. 



1852. Carcinoplacinae H. Milne-Edwards. Ann. Sc. Nat. (3), t. iS, p. 164. 



1886. Carcinoplacinae Miers. Rep. '"Challenger", Brachyura, p. 223. 



1900. Pseudorlionibilinac Alcock. Journ. As. Soc. Bengal, v. 69, prt 2, p. 286, 292. 



Alcock enumerates, though sometimes with a query, fifteen genera of the subfamily, 

 removing at the same time Geryon Kröyer and Camptoplax Miers, that are referred to the 

 Xanthidae. Of these fifteen genera Brachygrapstis King.sley is almost certainly identical with 

 Litochcira Kinahan, Caniptandriuin Stimpson has now turned out to be one of the Ocypodidae 

 (see p. 68 of the first part of the present paper), Cryptocoeloma Miers is very little known and 

 has been doubtfully referred by Miers himself to the Rhizopinae, Heteroplax Stimpson is most 

 likely synonymous with Encratc de Haan, and Platypihtmnns Wood-Mason seems to belong 

 to the Xanthidae. 



So there remain ten genera, of which two, viz. Frevillea A. Milne-Edwards") (not Frey- 

 villea as Alcock spells it) with three species, and Bathyplax A. Milne-Edwards^) with a single 

 one *), are Atlantic and live on the western side of this ocean. Miss R.\thbun afterwards added 

 two new genera, Tetraplax '), with one species, from the West Indies, and Trizocarcinus "), 

 likewise with one species, from the Gulf of California. All these American genera, except perhaps 

 the last, are most incompletely known and, except for Bathyplax and Trizocarcinus, have 

 never been fig-ured. 



This subfamily, like the Prionopla'cinac, has the utmost afhnity with such Xanthoid forms 

 like Eucraiodes A. Milne-Edwards and indeed it is nearl)- impossible to tracé a distinct boundary; 

 on the other hand the genus Cafoptrns A. ?^Iilne-Edwards is perhaps better to be referred to 

 the Portunidae. 



I have here. following Alcock, retained the name of the subfamily, but the genus 



1) K. Dansk. Vid. Selsk. Skr., 7. Raekke, Afd. 5. n» 4, 1910, p. 345. 



2) BuU. Mus. corap. Zool. Haivard CoU., v. 8, 1880, p. 15. 



3) L. c, p. 16. 



4) Miers (Rep. "Challenger", Brachyura. 1SS6. p. 230, pL 20, f. 3) describes a subspecies. 



5) Buil. l'.S. Fish Comm. for 1900, v. 2, 1901. p. 9. The lype is Frevillea ijiiaiiriilaita/a Rathbun, BuU. Lab. Nat. Hist. State 

 L'n. lowa, v. 4, 1898, p. 287, p. 8, f. I. 



6) Proc. U.S. Nat. Mus., v. 47, 1914, p. 117, te.\tfig. i, pi. i. The type is Carcbtoplax Jentata Rathbun, Proc. CS. Nat. Mus., 

 V. 16, 1S93, p. 243. 



S 



