700 DR. G. S. BRADY ON BNTOMOSTRACA [June 19, 



Oyprinotus sarsi, sp. n. (Plate LI. figs. 1-11.) 



Shell of the female, seen laterally (fig. 1), subreniform, highest 

 near the middle, height equal to more than half the length ; 

 anterior extremity narrower than the posterior, evenly rounded ; 

 posterior wider, rounded ofi' below, sloping with a steep curve 

 above; dorsal margin boldly arched, almost gibboiis, highest in 

 the middle, thence sloping rather steeply and almost in a right 

 line toward the front and with a more gentle curve backwards ; 

 ventral margin slightly sinuated in the middle. Seen from above 

 (fig, 2) the outline is elongate- ovate, moi'e than twice as long as 

 broad, the greatest width in the middle ; lateral margins evenly 

 curved, anterior extremity obtuse, posterior subacuminate. 

 Surface of the shell smooth, rather densely clothed at the anterior 

 extremity with very fine, silky hairs, very spaiingly hairy behind ; 

 colour creamy bufi", profusely blotched or almost covered with 

 patches of dai-k brown. The valves of the two sides are equal 

 or nearly equal in size, without any overlapping dorsally or at the 

 extremities ; the right valve is veiy feebly — almost imperceptibly 



. tuberculated round the postero-ventral angle. Length 1 "4 nnn. 



The swimming-setfe of the posterior antennte (fig. 4) reach slightly 

 beyond the apices of the claws ; caudal rami (fig. 1 0) veiy slender, 

 bearing one very long and one shoi't apical seta and two posterior 

 marginal sette, both of which are closely approximated to the 

 apex. 



The shell of the mcde (fig. 3) is smaller and higher in proportion 

 to length than that of the female. The maxillae of both sides 

 (fio's. 6, 7) are strongly built, that of the right side bearing a 

 very strong, falcate terminal claw, that of the left side a triangular 

 plate which ends in a slightly hooked prominence ; copulative 

 organs (fig. 11) and ejaculatory duct of the usual type. 



Habitat. Taupo Lake. About eight specimens divided evenly 

 between the two sexes : taken by " netting on bottom in a depth 

 of 5-25 feet — sandy, with patches of weeds." 



So far as the soft parts of the animal are concerned, thei'e is 

 little or nothing to distinguish this species from CT/j^rinoius 

 dahli G. 0. Sars, but the characters of the shell difier in some 

 important points. There is not the veiy steep posterior declivity 

 of C. dahli nor the marked convexity of the ventral margin : 

 moreover, the valves of the two sides are nearly equal and the 

 rio'ht valve is not raised dorsally above the level of the left, neither 

 is there any tuberculation of the margins except perhaps a 

 very indistinct appearance of it at the anterior extremity of the 

 rioht valve. The New Zealand shells, as they reached me, Avere 

 very thin and membranous in structure, but this Avas probablj'' a 

 consequence of their having been preserved in picric acid. The 

 specimens of Cyprinotus dahli* on which Professor G. 0. Sars 

 founded the species were raised by him in his laboratory from 



* G. 0. Sars, " On some West-Anstralian Entomostvaca raised from dried sand " 

 •(Archiv f, Mathem. og Natnrvidenslvab), 1896, p. 24, pi. iv. figs. 1-5. 



