REPORT ON THE OSTRACODA. 157 



arched behind, flattened, and sloping almost in a right line towards the front, ventral 

 margin regularly convex ; the greatest height is situated in the middle and is equal to 

 about three-fourths of the length ; seen from above, the outline approaches a lozenge 

 shape, is widest in the middle, and tapered to the extremities, which are acuminate ; the 

 lateral margins evenly curved, and slightly sinuated towards the posterior extremity ; 

 width equal to half the length ; end-view oval, width equal to two-thirds of the height. 

 Surface of the shell smooth, and covered with minute closely-set punctations. The ribbed 

 markings and patches shown in the plate are probably the result of shrinkage of the more 

 delicate parts of the shell in drying. The texture of the shell is tolerably firm, and cal- 

 careous over the greater portion of its area ; but some parts, more especially along the 

 ventral and posterior margins, are thinner and submembranaceous. Length, 23-lOOths of 

 an inch (6 mm.). The anatomical structure is in every way like that of the preceding 

 species. One specimen only dredged off Kerguelen Island, in a depth of 120 fathoms. 

 I have much pleasure in dedicating this fine species to the author of the " Crustacea of 

 the United States' Exploring Expedition." 



[PI. XXXVI. fig. 2, a-d. a Carapace seen from left side, h from above, c from below, 

 d from front. Magnified 10 diameters.] 



Crossox->hovus^ n. gen. 



Shape of the shell as in Oypridina, the posterior extremity broadly rounded ; texture 

 firm and calcareous ; anterior antenna six-jointed, the second, third, and fourth joints 

 fringed with short setae on the upper, and each bearing a fascicle of setae on the lower 

 margin ; fifth joint bearing one long ringed " auditory " seta, the last joint four long and 

 several shorter setse of similar character. Posterior antennae as in Cyiyridina, except 

 that the secondary branch (PL XXXVIII. fig. 5, a) is powerfully clawed, the last joint 

 forming a strongly-curved o^^posable claw ; the first and second joints are robust, and 

 each bear fascicles of short, stout setse. The mandibular foot (fig. 6) is armed at the 

 apex of the basal joint with a bifurcated hairy process, the second joint is very broad, 

 bearing a few marginal setae, and near the apex a transverse crescentic row of twelve 

 haixs, which gradually increase in length from within outwards ; at the apical angle of 

 its outer margin is a slender digitiform process which has two terminal setae ; the third 

 joint is very short and broad, and bears a fringe of about six long setae ; the last joint is 

 long, slender, densely setose on its outer half, and has an apical fringe of about eight or 

 ten stout setae, and three or four strong curved spines, these latter being fixed to the outer 

 angle. The first pair of maxiUae (fig. 7) consist of one principal biarticulate branch, and 

 several smaller segments ; all these are abundantly setiferous, and the apical joint of the 

 main branch bears also several short claw-like spines ; the second pair- of maxillas (fig. 8) 



' K^oaoi, fringe ; (pi^a, T carry. 



