214 DR. G. S. BRADY ON THE [Feb. 1, 



Prionocypris tumefacta Brady & Robertson. (Plate XXVIII. 

 figs. 1-3.) 



1870. Gypris tumefacta Brady & Robertson, Ostracoda and 

 Foraminifera of Tidal Rivers (Ann. & Mag. Nat. Hist, 

 ser. 4, vol. vi.) p. 13, pi. iv. figs. 4-6. 



1889. Erpetocypris tumefacta Brady & Norman, (2) Part i. 

 p. 87, pi. viii. figs. 5-7, pi. xiii. fig. 18. 



1900. Cypi-is tumefacta G. W. Midler, (5) p. 73, pi. xvii. 

 figs. 4, 8, 13. 



1900. Prionocypris tumefacta Kaufmann, (4) p. 295, pi. xvi. 

 figs. 13-15, pi. xxi. figs. 9-13. 



Shell, seen laterally, subreniform, highest in the middle, height 

 greater than half the length ; extremities rounded, the posterior 

 much the broader of the two ; dorsal margin arched, sloping more 

 abruptly behind than in front : seen from above the outline is 

 ovate, excessively tumid, width equal to two-thirds of the length ; 

 anterior extremity abruptly tapered and forming a mucronate 

 prominence, posterior broadly rounded ; the two valves are nearly 

 equal in size but have the two extremities and, in a smaller degree, 

 the ventral margin incurved so as to form a very conspicuous 

 flange or duplicative (fig. 1). Shell-surface quite smooth, colour 

 white. Length 1'05 mm. 



Setee of the posterior antenna? very short, arranged in a distinct 

 fascicle of four (fig. 2) ; caudal rami (fig. 3) slender, the two 

 terminal claws equal in length, and almost imperceptibly pectin- 

 ated, marginal seta very small and not far removed from the 

 claws. 



A very well marked species, recognizable at a glance by its 

 excessive tumidity and produced anterior extremity. The internal 

 duplicative of the margins of the valves is more pronounced than 

 in any other species known to me. 



I have taken it in the Warn Burn, Northumberland, near 

 Sunderland, and in the River Lathkill, Derbyshire; it has been 

 found also by the late Dr. Robertson and by Dr. Thos. Scott in 

 several Scottish localities. 



Genus Ilyodromus G. O. Sars. 



Shell highly compressed, and, seen laterally, oblong ; dorsal edge 

 straight in the middle, ventral sinuated. Valves generally not 

 very unequal, the left the larger ; surface usually longitudinally 

 striated. Seta? of the inferior antennas poorly developed, not 

 reaching beyond the terminal claws. Caudal rami coarse, armed 

 with three strong claws increasing in length distally. Animal 

 devoid of swimming power. Propagation parthenogenetical. 



This generic definition is slightly condensed from that given by 

 G. O. Sars in a paper on the " Freshwater Entomostraca of New 

 Zealand," 1894. As applying to the British species, the state- 

 ments as to the straight dorsal edge and longitudinal striation 



