TWO COMMON SPECIES OF ^t^^^mC CRU^^^ 

 (SACCULINIDAE) OF THE WEST INDIES 



By H. BoscHMA 



Of the University of Leiden, Holland 



The chief characteristics defining the genera of the Ehizocephala 

 concern the shape and the situation of the internal organs One of 

 rLost impoSant is the manner in which the -scera .nas= ^ 

 attached to the mantle by a mesentery, which may he tl m am 

 Sa^cuUn^ and allied genera, or thicker, a^ m ^f'^'^f'-^^^J^Z 

 parasites of the gi-oup. Smith (1906), the author o a mono^aph 

 on the Ehizocephala, based the taxonomy of the group for a large 

 par on the differences in the size and the plaa. of the mesentery^ 

 This author created the new generic name Heeromccns, the type 

 species of which is Sa.eulina^ h«ns Kossmann which '= dra^-^"-'' 

 by a very short mesentery. In this species it is confined to the mme 

 dkte vicinity of the stalk only. According to Smith the internal 

 ^rulture of the other parasites of the group which '-e on crabs does 

 not show any morpliological differences, and consequently he umted 

 ^h m Zder'the name So.e^ caroM. In this -spect, howeve^ 

 Smith's conclusions are wrong, for there are a number of species 

 which can be distinguished from S. cardm by constant morphological 



*' The mesentery of Sacmdina cardni is complete; it stretches from 

 the stalk to the mantle opening. In some other parasites, which 

 have been described as species of the genus^Wi-, «« -sentery 

 is incomplete, for it terminates at some distance from the mantle 

 LZg Fo these species of Sacculinidae with incomplete mesen- 

 tery, in a recent paper (Boschma, 1927) I have founded the new 

 g^n'us Drepanorcll, the type species of which is D. -^^*- (f^^^ 

 Unu negleota Fraisse). Another constant feature of all the species 

 belonging to this genus is found in the shape of the testes, they are 

 curved, whereas in ^*»K«« they consist of more or less straight 



'"There are a few species of Sacculinidae which in some respecte 

 constitute intermediateJorms_betweenMth^^en^^ 



NO. 2726;^ROOCED1NQS U. S. NATIONAL MUSEUM, VOL. 73. ART. 5 ! > 



76867 — 28 



