Tlie Fresh-water Entomostraca of Cape Province. 341 



GEN. 13. EURYALONA, G. O. Sars. 



Bema rks This genus was established in the year 1901 by the 

 present author, to include a Ghydorus raised out of dried mud from 

 the Argentine, and named E. occidental, its true relation to the 

 previously described species, Alonopsis colletti, not being at that time 

 recognised. The genus is chiefly characterised by the broadly expanded 

 and quite smooth shell, as also by the slender form of the tail- 

 piece. 



41. EURYALONA COLLETTI (G. 0. Sars). 



(Plate XLI, tigs. 1, 1 , 6.) 



Alonopsis colletti, G. O. Sars. On some South African Entoniostraca 

 raised from dried mud. Chr. Vid. Selsk. Skrifter f. 1895, p. 22, pi. 4, 



figs. 5-8. 



Syn. : Euryalona occidental-is, G. O. Sars. 



Specific Characters Female. Shell, seen laterally, broadly quad- 

 rangular in outline, with the dorsal margin evenly arched, ventral 

 slightly flexuose, posterior extremity obtusely truncated, with the 

 upper corner obtuse-angular, the lower rounded off. Head com- 

 paratively small and slightly procumbent, with the rostral corner 

 not much produced and pointing obliquely forward. Surface of 

 valves smooth, without any obvious sculpture, except a faint concen- 

 tric dotting near the free edges. Ocellus a little smaller than the eye 

 and located nearly midway between it and the tip of the rostrum. 

 Anteuiiulae comparatively small, not nearly extending as far as the 

 latter. Tail-piece very slender and elongated , slightly tapering distally , 

 and deeply incised at the end, with the hind corner rather prominent ; 

 supra-anal angle slight and far remote from the middle ; marginal 

 denticles well developed and equal-sized, sub-marginal combs only 

 faintly indicated ; apical claws slender and only slightly curved, each 

 round at the base with a single rather large denticle ; outer part of the 

 claws quite smooth. 



Colour more or less dark yellowish-brown. 



Length of shell somewhat exceeding 1 mm. 



Remarks. I have convinced myself of the complete identity of the 

 South African and South American forms, and, of course, the specific 

 name at first proposed ought to be retained for the present species. 

 The form recorded by Dr. Daday from Ceylon as Alonopsis orientals 

 is evidently congeneric, but differs, according to the figures given by 

 that author, both in the general form of the shell and in the armature 



