146 Annals of the SoutJi African 



FAMILY DIASTYLID^E. 



1856. DiastylidcB (part), Bate, Ann. Nat. Hist., Ser. 2, vol. xvii. 



p. 449. 

 1900. D. (part), G. 0. Sars, Crustacea of Norway, vol. iii., p. 41. 



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

 apical spines ; accessory flagellum of first antennae distinct ; man- 

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

 palp ; branchial leaflets numerous, often spirally arranged ; exopods 

 on the first four pairs of peraeopods 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; Leptostylis, Sars, 1869; Diastylopsis, S. I. 



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



Adiastylis, Makrokylindrus, and EJcleptostylis. 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, Ekdiastylis, in 



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



species transferred from Diastylis. Holostylis in the Holostylidae is 



instituted to receive Diastylis heller i, Zimmer, 1907, and with it 



( 'nma gayi, Nicolet, 1849, both of which are set forth as having 



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



the Diastyloididte 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 Pseudo- 



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



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



stylidse, 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 " Colurostylis (?) occidentalis," Caiman, 1912, has that ramus 



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



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



originally assigned to the genus Gynodiaxti/lix, Caiman, 1911, agree 



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



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



