REPORT ON THE OSTRACODA. 85 



ditions which have at length resulted in similar peculiarities of structure. The same 

 observation applies with equal force to several of the ribbed species which come next to 

 be described. 



[PL XII. fig. 4, a-d. a Shell seen from left side, h from below, c from above, d from 

 front. All magnified 60 diameters.] 



40. Cythere lauta, n. sp. (PI. XXI. fig. 4, a-d). 



Shell, seen from the side, oblong, subqnadrate, the greatest height being situated over 

 the anterior hinge-joint, and equalling at least half the length ; anterior extremity- 

 well rounded and crenulated, posterior truncated and irregularly notched, lower angle 

 rounded ofi"; dorsal margin sinking rather abruptly behind the anterior hinge, thence 

 sloping gently with an irregularly notched line to the hinder end where it is abruptly 

 angular, ventral margin slightly sinuated ; seen from above, the outline is clavate, nearly 

 thrice as long as broad, the sides parallel, suddenly converging in front of the middle, 

 then running again directly forwards and forming a broad truncated anterior extremity ; 

 the posterior extremity forms a short truncated and notched prominence rather broader 

 than that of the anterior ; end view irregularly quadrangular, the dorsal and ventral 

 margins convex, sides concave. The margins of the shell are produced and form a thick, 

 flattened, and dentated flange, this being most fully develojDcd at the two extremities, 

 and much expanded on the ventral surface ; the remaining central portion of the valve 

 forms a somewhat elliptical area, and is marked ofi" more or less perfectly by elevated 

 ridges ; there is also an oblique longitudinal ridge occupying the posterior half of the 

 middle line, the rest of the surface being marked by angular excavations. Length, 1-5 2d 

 of an inch ("49 mm.). 



Found only in the Booby Island dredging, from lat. 10° 36' S., long. 141° 55' E., 

 6 to 8 fathoms. (Station 187.) 



[PI. XXI. fig. 4, a-d. a Shell seen from left side, b from above, c from below, d from 

 front. Magnified 60 diameters.] 



41. Cythere stiinpsoni, G. S. Brady (PI. XXI. fig. 6, a-h). 



Cijthere stimi^soni, Brady, Les Fonds de la Mer, torn. i. p. 78, pi. x. figs. 7, 8, and Ann. and 

 Mag. Nat. Hist., ser. 4, 1869, vol. iii. p. 48, pi. vii. figs. 9-12. 



Carapace of the female, seen from the side, oblong, subclavate, higher in fi'ont than 

 behind, greatest height situated over the anterior hinge, and equal to half the length ; 

 anterior extremity broadly rounded, bordered with numerous more or less strongly 

 developed spines, posterior much narrower, somewhat angular in the middle, toothed 

 below the middle ; dorsal margin gil^bous over the anterior hinge, thence sloping with a 

 gentle curve backward ; ventral margin nearly straight ; seen from above, the outline 

 forms a narrow parallelogram with two nearly equally broad, produced extremities, width 



