MARINE OSTRACODA FROM MADEIRA. 597 



ventral slightly sinuated in the middle : seen from above (fig. 6) 

 the outline is oblong, with straight, parallel, lateral margins and 

 strongly produced extremities ; the margins converge steeply in 

 front terminating in a stout median pi-ocess, behind they converge 

 almost rectangularly and form a veiy wide central hump. Sur- 

 face of the shell covered with rounded and closely-set impressed 

 pittings, and bordered in front and behind with a smooth 

 depressed fillet. Length 0-78 mm. 



One specimen dredged in 30 fathoms, and one in 70 fathoms. 



Cythereis deformis, sp. n. (Plate XX. figs. 7, 8.) 



Shell, seen laterally, oblong, subquadrate, greatest height 

 situated near the front and equal to nearly half the length (fig. 7) ; 

 anterior extremity well rounded and bordered with a series of 

 short, blunt teeth ; posterior extremity much narrower, truncated, 

 prominently angular in the middle and divided below the middle 

 into a few irregulai'ly tooth-like processes ; dorsal mai-gin sloping 

 gradually from the front backwards, ventral margin almost 

 straight: seen from above (fig. 8) the outline is compressed, 

 oblong, about thrice as long as broad, the lateral mai'gins very 

 irregular, with a sharply prominent angle at the posterior third ; 

 extremities much produced, broadly truncate, with irregularly 

 dentate margins. Shell-surface irregularly rugose, with a wide 

 depressed band stretching roimd and within the anterior margin ; 

 a shai'ply elevated crest running obliqiiel}'' across the posterior 

 half and terminating in a sharply produced angle on its dorsal 

 aspect. Length 0"5 mm. 



Dredged in 70 fathoms. 



It is imj^ossible, by the shell-characters alone, to separ.ate clearly 

 the species belonging to the two genera Cythere and Cythereis as 

 they are now understood by most authors, nor, as it appears to 

 me, are the distinctive charactei'S of the contained animal much 

 more satisfactory. 



LoxocoNCHA OBESA, sp. n. (Plate XXI. figs. 3, 4.) 



Shell, seen laterally, elliptical, greatest height situated in the 

 middle and equal to half the length (fig. 3) ; extremities evenly 

 rounded, the posterior somewhat the narrower of the two ; dorsal 

 margin veiy slightly arcuate, ventral almost straight, not at all 

 sinuated : seen from above (fig. 4) the outline is veiy broadly oval 

 with strongly produced mucronate extremities, width considerably 

 exceeding half the length, lateral margins very strongly convex. 

 Shell-surface perfectly smooth. Colour grey. Length 0"46 mm. 



Dredged in 70 fathoms ; one specimen only. 



LoxocoNCHA decipiexs G. W. Miiller. (Plate XXL figs. 1, 2.) 



Several specimens, agreeing very accurately with the figures 

 given by Dr. G. W. Miiller, were dredged in 70 fathoms. One 

 quite charactei'istic specimen is figured here. 



