REPORT ON THE OSTEACODA. 



101 



The species is evidently ubiquitous, or nearly so, in the deep sea, the foregoing list of 

 localities extending over the North and South Atlantic, the Indian, and Pacific Oceans ; 

 in very shallow water it is uniformly wanting, the smallest depth in its list of habitats 

 being 120 fathoms, while the greater number of the dredgings in which it occurs range 

 from 1000 to 2000 fathoms. 



[PI. XXIV. fig. 1, a~y. Figures a-d are drawn from a female shell, and e-g from a 

 male of the common type ; figures h, i show a variety of the female with well-developed 

 posterior spines (Station 280) ; figures j, h are from valves of a diiferent type (Station 

 296) ; figures v-y are drawn from a very strongly-sculptured specimen of extreme type 

 (Station 191a); the figures from I to u exhibit various stages of growth, and are from 

 Station 300. AU magnified 40 diameters, except v-y, which are x 50.1 



68. Cythere arata, n. sp. (PL XXIV. fig. 2, a-c). 



Valves, seen from the side, subquadrangular, ecpal in height throughout ; anterior 

 extremity obliquely rounded, and bearing numerous short marginal teeth ; posterior 

 subtruncate, irregularly spinous, sloping steeply forwards above the middle to its upper 

 termination, where it is strongly angulated and bears a prominent spine ; dorsal margin 

 more or less sinuated and dentate, ventral slightly convex, and forming a sharp ridge 

 which ends posteriorly in a strong spine ; seen from above, the margin of the valve forms 

 a tolerably regular curve, and is widest behind the middle where there is a conspicuous 

 spine. SheU-surface marked with minute scattered puncta, in the middle mth several 

 transverse furrows, within the ventral and anterior margins with a number of irregular 

 deep fossae. Length, l-24th of an inch (r05 mm.). 



A few valves only of this species were found in a dredging from a depth of 150 

 fathoms, lat. 39° 32' S., long. 171° 48' E. (Station 167). Though more angular in 

 outline than any examples of Cythere dictyon which I have yet seen, it yet closety 

 approaches that species; but the style of surface ornament is entirely different, both 

 from Cythere dictyon, and, so far as I know, from all other species. 



[PI. XXIV. fig. 2, a-c. a Left valve seen from side, h from above, c right valve seen 

 from side. Magnified 40 diameters.] 



69. Cythere normani, G. S. Brady (PL XVII. fig. 3, a-d, and (?) PL XXVI. fig. 4, a, 6). 



Cythere normani, Brady, Trans. Zool. Soc, 1865, vol. v. p. 379, pi. Ixi. fig. 5, a-d. 

 Valves, seen laterally, trapezoidal, slightly higher in front than Ijchind, height equal 



