﻿146 Antials of the SoiitJi African Miiscnm. 



Family DrASTYLID.E. 



1856. DiastyluJte (part), Bate, Ann. Nat. Hist., Sor. 2, vol. wii. 



p. 449. 

 1900. D. (part), G. O. Sars, Crustacea of Norway, vol. iii., p. 41. 



All the pedigerous segments distinct ; telson large, with only two 

 apical spines; accessDry flagelluin of first antennae distinct; man- 

 dibles normal, not broad at the base ; first maxillae with bisetose 

 palp; branchial leafiets numerous, often spirally arranged ; exopods 

 on the first four pairs of perueopods in the male, on the first two 

 pairs in the female and sometimes rudiments on the third and fourth 

 pairs ; two pairs of biramose pleopods in the male ; inner branch 

 of uropods three-jointed. 



With this definition the family will be restricted to the genera 

 Diastylis, Say, 1818; Lcptostylis, Sars, 1869; Diastijlopsis, S. I. 

 Smith, 1880; ParacUastylis, Caiman, 1904; and the new genera 

 Adiastylis, Malcrohylindrus, and Ekleptostylis. But this compact- 

 ness has to be purchased at the cost of establishing several new 

 families closely allied in most of their features. Thus a two-jointed 

 inner ramus of the uropods introduces a new genus, Ekdiastylh, in 

 the Ekdiastylidffi, with E. sculptus (Sars), 1871, and eight companion 

 species transferred from Diastylis. Holostylis in the Holostylidae is 

 instituted to receive Diastylis helleri, Zimmer, 1907, and with it 

 Cmna gayi, Nicolet, 1849, both of which are set forth as having 

 a simple inner ramus to the uropods. In Diastyloides, Sars, 1900, 

 the Diastyloididae have a genus in which the mandibles are broad at 

 the base instead of normally tapering, and the second pleopod has 

 only a single ramus. The Pseudodiastylidae, dependent on Pseiido- 

 diastylis ferox, Caiman, 1905, known only in the female sex, have 

 an elongate telson with more than two apical spines. In the Oxyuro- 

 stylidae, Oxyurostylis smithi, a new genus and species, established 

 by Dr. Caiman in 1912, exhibits a sharply pointed telson with no 

 apical spine or spines. The Colurostylidae, in the original repre- 

 sentative Colurostylis pseudocuma, Caiman, 1911, have a short telson 

 without apical spines and a two-jointed inner ramus to the uropods, 

 but " Cohirostyiis (?) occidentalis," Caiman, 1912, has that ramus 

 three-jointed. The Gynodiastylidae are separated from all the fami- 

 lies just mentioned by having no pleopods in the male. The species 

 originally assigned to the genus Gy?wdiastylis, Caiman, 1911, agree 

 in having a rather small, unarmed telson not produced beyond the 

 anus, and as in Paradiaslylis with no exopod to the third maxillipeds 



