245 



Subfam.. Pinnütherinae. 



This group contains the most typical representatives and is immediately recognizable by 

 the shape of the external maxilHpeds, besides by the carapace being- nearly alvvays of a parch- 

 ment-Hke consistence and subcircular or indistinctly angular, but without sharpened lateral 

 margins, which never present teeth or notches. 



Key to the genera : 



1. Palp of ext. maxilHpeds twojointed only, the dactylus being 



absent 2 



Palp of ext. maxilHpeds three-jointed, the dactylus being 

 generally inserted at the inner side of the propodus . 4 



2. Terminal joint of palp of ext. maxilHpeds widening distally. 3 

 Terminal joint of palp of ext. maxilHpeds not widening 



distally Ostracotheres H. Milne-Edwards 



3. Dactyli of walking legs, except those of last pair, deeply 



bifurcate Dissodactylus S. J. Smith 



Dactyli of walking legs simple, about as long as propodites. 



Orbits ventral in position. Carapace well calcified . . Cryptophrys Rathbun 



4. Lateral margins of carapace thickened, upturned ... 5 

 Lateral margins of carapace not upturned 6 



5. Middle of carapace with a prominent tubercle, shaped like 



a mushroom and reniform Xanthasia White 



Middle of carapace with a longitudinal ridge .... Dürckheimia (Rüppell) de Man 

 6' Propodus of ext. maxillipeds longer than merus. Carapace 



well calcified Scleroplax Rathbun 



Propodus of ext. maxilHpeds much shorter than merus. 



Carapace parchment-like 7 



7. Longitudinal grooves on the carapace, beginning behind 



the orbits Raphonotus Rathbun 



No longitudinal grooves on the carapace Pinnotheres Latreille 



Dissodactylus S. J. Smith. 



1870. Dissodactylus S. J. Smith. Transact. Connecticut Ac, v. 2, p. 172. 

 1900. Echinophilus Rathbun. Am. Natur., v. 34, p. 590. 



The typical species is Dissodactylus nitidns S. J. Smith, 1. c, p. 173, found at Panama. 

 Afterwards Miss R.\thbun records it from Lower California ^) and from Peru "). 



A second species is Dissodactylus mellitae Rathbun, 1. c, and a third Dissodactylus 

 encopci Rathbun, Buil., \5 . S. Fish Comm. for 1900, v. 2, 1901, p. 22, textfig. 5; both these 

 species are associated with Echinids and occur in West Indian waters. 



1) Proc. U. S. Nat. Mus., v. 21, 1899, p. 609. 



2) Proc. U. S. Nat. Mus., v. 38, 1910, p. 545, pi. 48, f. 6. 



97 



SIBOGA-EXPEDITIE XXXIX c'. 32 



