REPORT ON THE OSTRACODA. 71 



projection of the hinder portion of the valves ; the dorsal surface is elevated along the 

 liinge-line into a prominent ridge ; the ventral surface keeled in a similar manner, and 

 having the valve-margins exjjanded so as to form a flattened flange anteriorly ; end 

 view triangular, the angles rounded off, the lateral margins arched, and the ventral 

 margin bisinuate ; surface of the shell sculptured throughout with subrotund excavations 

 of moderate size and rather closely set ; the valves gradually elevated l^ehind the 

 middle so as to form a rather prominent alseform protuberance. Length, l-62d of an 

 inch (•41 mm.). 



A well marked but small species, distinguished by the broadly truncated extremities 

 and the alteform lateral elevations of the valves. It was noticed only in a dredging from 

 Torres Straits, depth 155 fathoms, sand. (Station 185.) 



[PL XIII. fig. 1, a-d. a Shell seen from left side, h from above, c from below, d from 

 front. Magnified 60 diameters.] 



17. Cythere cumulus, n. sp. (PL XIII. fig. 2, a-d). 



Shell oblong, tumid ; seen from the side, subquadrangular, not much higher in front 

 than behind, height equal to a little more than half the length ; anterior extremity well 

 rounded; posterior rounded and narrow ; dorsal margin straight ; ventral straight through- 

 out the greater pai't of its course, but turned abruptly upwards at an obtuse angle at 

 the posterior extremity ; seen from above the outline is boat-shaped, tapering abruptly 

 in front, scarcely at all behind, sides nearly straight and parallel ; anterior extremity 

 obtusely pointed, posterior broad and rounded off, but having a small mucronate pro- 

 jection in the middle, width ecjual to the height ; the end view is in the form of a high 

 arch with a slightly convex base, the sides being nearly straight below the middle. Sur- 

 face of the shell thickly covered with deep angular excavations. Length, l-50th of an 

 inch ('5 mm.). 



The only dredging in which Cythere cumulus occurred is that from Port Jackson, 

 2 to 10 fathoms. 



[PL XIII. fig. 2, a-d. a Shell seen from left side, h from above, c from below, d from 

 front. Magnified 50 diameters.] 



18. Cythere Jlos-cardui, n. sp. (PL XIII. fig. 3, a-li). 



Carapace of the female, as seen from the side, subcj^uadrangular, higher in front than 

 behind, the greatest height situated near the anterior extremity and equal to nearly two- 

 thirds of the length ; anterior extremity broad and obhquely rounded, posterior narrower, 

 oblique, scarcely rounded, looking slightly upwards ; dorsal margin slightly arched, sloping 

 gently iDackwards, and terminating in a distinct angle, ventral nearly straight, bent 

 upwards at the posterior extremity ; seen from above, ovate, with suljparallel sides, 

 twice as long as broad ; anterior extremity narrow, rounded off, and mucronate in the 



