l895- ^'o. 8. SOUTH-AFRICAN ENTOMOSTRACA. 5 



just within the angular bend of the front; ocellus very minute. Anten- 

 nulae in female small, though distinctly projecting; in male, as usual, much 

 larger, though not attaining the length of the head, flagellum rather short. 

 Tail in female with the dorsal lappets very largely developed, the 2 

 upper ones contiguous at the base, the 2 lower confluent; terminal part 

 conically tapering, with the dorsal edge nearly straight, anal denticles 

 subequal, i8 — 2o on each side, terminal claws comparatively short and 

 stout, spinulose at the base. Tail in male without any dorsal lappets 

 terminal part but little differing from that in female. Ephippium drawn 

 out anteriorly to a long spinulose strip, ampullae obliquely disposed. 

 Body in both sexes pellucid, with a faint greenish or yellowish tinge. 

 Length of adult female reaching 3 mm., of male 1,20 mm. 



Remarks. This is a very distinct species, which exhibits some points 

 of resemblance to the D. Atkinsoni Baird, though evidently specifically 

 different. The specific name refers to the peculiar form of the head in 

 the female. 



Description of the female. 



The largest specimens measure in length, excluding the spine, about 

 3 mm., and this form accordingly grows to a rather large size, though 

 being in this respect somewhat inferior to D. Thomsoni. 



As in most other species, the carapace is rather compressed ;^see 

 fig. i", the greatest width but little exceeding half the height. In a lateral 

 view of the animal (fig. 2), it exhibits an oblong oval form, with the 

 ventral margin in ever}' case more curved than the dorsal one, which 

 latter, even when the matrix is distended with ova or embryos, does not 

 form any considerable cun'ature. The posterior part of the carapace is 

 gradually narrowed, and is continued into the usual spiniform process. The 

 latter is quite straight, and issues somewhat above the longitudinal axis. 

 It is generally obliquely upturned, and of somewhat variable length, being 

 in some individuals, especially of the earlier generations, about half as long 

 as the carapace, whereas in other specimens it becomes quite short and 

 stout. The edges of the valves are in their posterior halves denselj'' 

 clothed with small, appressed denticles, and similar denticles also occur 

 along the whole dorsal edge, being in some instances even continued on 

 the posterior part of the head, especially in specimens with ephippium 

 (see fig. 10}. The spine of the carapace has, as usual, 4 rows of appres- 

 sed spinules. The surface of the shell is densely reticulated with 2 sets 

 of curv'ed striae crossing each other at ntarly right angles. In the anterior 

 part of the valves the sigmoid shell-gland may be easily traced. 



