76 Gr- 0- Sårs. 



additional Australian Oladocera». Another very nearly allied 

 species had somewhat previously been detected in North 

 America by Prof. Birge, who at first recorded it under the 

 name Crepidocercus setlger, and the same species was sub- 

 sequently found in Hungary by Mr. Daday. I now propose 

 to describe an additional form from South America, which I 

 believe is distinct from any of the others. 



40. Dunheyedia odontoplax, n. sp. 



(PI. XI, figs. 6, a— b). 

 Specific Characters. — Female. Carapace, 

 seen laterally, broadly oval, or somewhat elliptical in out- 

 line, height not quite equal to the length, dorsal margin 

 well arched, ventral bulging in front, but almost straight in 

 the middle, posterior extremity somewhat narrowed and ob- 

 tusely truncated at the end, hind edges slightly convex be- 

 low. Head rather broad and not very procumbent, its 

 dorsal margin continuous with that of the carapace, both 

 forming together a perfectly even and uninterrupted curve up 

 to the tip of the rostrum, the latter rather short. Surface of 

 shell exhibiting a very faint reticulation, lower edges of valves 

 densely fringed in the middle with very delicate cilia, infero- 

 posteal corners produced to a well-marked dentiform pro- 

 jection. Eye comparatively large, with some of the crystal- 

 line cones very distinct; ocellus much smaller than the eye. 

 Lip-plate with a very conspicuous dentiform projection at 

 about the middle of the lower edge. Caudal part, as in the 

 other species of this genus, curved in a peculiar manner, 

 being almost angularly bent in the middle, ventral edge 

 deeply sinuated above, dorsal forming in the middle a rounded, 

 heel-shaped protuberance, supra anal projection inconspicuous, 



