108 THE VOYAGE OF H.M.S. CHALLENGEE. 



80. Cythere melohesioides, G. S. Brady (PL XVIII. fig. 1, a-g). 



■ Cythere melohesioides, Brady, Les Fonds de la Mer, torn. i. p. 162, pi. xix. ligs. 10, 11. 

 Cythere nodulifera, Brady, Les Fouds de la Mer, torn. i. p. 163, pi., xix. figs. 24, 25. 



Shell, seen from the side, oblong ; height equal to half the length, the same before and 

 behind ; anterior extremity well rounded, posterior oblique, only slightly rounded ; dorsal 

 and ventral margins straight, the former much the shorter of the two owing to the 

 obliquity of the extremities ; seen from above the outline is compressed, oval, twice as 

 long as broad, widest about the middle, sides nearly parallel, and converging rather 

 suddenly to the extremities which are equal and broadly rounded ; end view subcircular ; 

 shell-surface everywhere rough with small subspinous nodules, from which structure the 

 margins of the shell in every aspect appear minutely dentated. Length, l-35th of an 

 inch (75 mm.). 



The foregoing description applies to the example shown in figures a-d, but not 

 c[uite accurately to e-g, which latter specimen shows some rather important difi'erences 

 chiefly in the lateral contour. Still it seems best for the present to consider both as 

 belonging to the same species ; possibly the difi'erences may be sexual. Figures a-d are 

 drawn from one of a series dredged off" Booby Island in a depth of 6 to 8 fathoms (Station 

 187), figures e-g from a single valve ; the latter agrees more closely than the other with 

 the specimens from Mauritius described in " Les Fonds de la Mer." 



[PI. XVIII. fig. 1, a-g. a Shell seen from left side, h from above, c from below, d 

 from front, e left valve (variety) seen from side, /from above, g from front. Magnified 50 

 diameters.] 



81. Cythere irrorata, n. sp. (PL XVIII. fig. 2, a-d). 



Shell oblong, tumid; seen from the side, subquadrangular, nearly equal in height 

 throughout, height equal to at least half the length ; anterior extremity rounded off abo^s^e 

 and below, posterior oblique, truncated, scarcely rounded, provided with a row of five or 

 six small blunt teeth below the middle ; dorsal margin very slightly arched, ending behind 

 in a prominent angle ; ventral margin nearly straight, but finely crenulated, as is also the 

 front of the shell ; seen from above, the outline is irregularly six-sided, nearly twice as 

 long as broad ; sides straight and parallel in the middle, converging suddenly in front, 

 and terminating in a broadly-rounded extremity, — behind the middle, converging abruptly 

 at a right angle, and then running obliquely backwards, and terminating much as in front ; 

 end view triangular, with very convex sides and rounded angles. The surface of the shell 

 is closely covered with small irregularly rounded nodules and flexuous grooves. Length, 

 l-42d of an inch ('6 mm.). 



This species was found only in one dredging from near the Admiralty Islands in a 

 depth of 16 to 25 fathoms. 



