128 THE VOYAGE OF H.M.S. CHALLENGER. 



from above, the outline is broadly ovate, pointed in front, and well rounded behind ; 

 width equal to the height ; end view obscurely angulated above, broad, and somewhat 

 emarginate below. Surface of the shell smooth, marked with a few distant small 

 papillae. Length, l-50th of an inch ('5 mm.). The shell represented in figures e-g is 

 perhaps referable to the male of this species, being found in company with the more 

 tumid form (figures a-d). The broken line shown by the artist in fig. 5, has been 

 inserted by mistake, probably from the accidental adhesion of some foreign body to 

 the shell. 



Xestoleberis margaritea has been met with only in one of the Challenger dredgings, 

 ofi" Booby Island, lat. 10° 36' S., long. 140° 55' E. ; 6 to 8 fathoms (Station 187). The 

 type-specimens are from the Mediterranean, where the species seems to be plentiful ; and 

 I have seen others from the Mauritius which are probably referable to the same. 



[PL XXX. fig. 2, a-g. a Carapace of the female, seen from left side, h from above, 

 c from below, d from front, e male (?), seen from left side, / from below, g from front. 

 All magnified 60 diameters.] 



9. Xestoleberis intermedia (?), G. S. Brady (PL XXXIII. fig. 2, a-d). 



Xestoleberis intermedia (?), Brady, Les Fonds de la Mer, torn. i. p. 94, pi. xii. figs. 3-7. 



Shell, seen from the side, subovate, depressed in front, highest in the middle, height 

 equal to more than half the length ; extremities rounded, the anterior narrower than the 

 posterior ; dorsal margin boldly arched, ventral gently convex ; seen from above, the 

 outline is regularly ovate, widest near the middle, the width equal to the height ; 

 extremities acuminate, the posterior, however, broader than the anterior ; end view 

 subcircular. Surface of the shell smooth, and ornamented with a few scattered circular 

 papillae, each of which bears a minute seta. Length, l-70th of an inch ("37 mm.). 



Found in Torres' Straits, lat. 11° 35' S., long. 144° 3' E., 155 fathoms (Station 185). 



The few specimens referred to in the foregoing description diflfer to some extent from 

 the type-specimens of Xestoleberis intermedia, especially in being much smaller, and in 

 the convex character of the ventral surface. I have thought it better, however, to assign 

 them to that species, than to coin a new name, on what might probably prove to be 

 insufiicient grounds. 



[PL XXXIII. fig. 2, a-d. a Shell seen from left side, b from above, c from below, 

 d from front. All magnified 80 diameters.] 



10. Xestoleberis tumefacta, n. sp. (PL XXXI. fig. 4, a-d). 



Carapace tumid ; seen from the side, subovate, not much higher behind than in front, 

 height equal to two-thirds of the length ; extremities obliquely rounded, dorsal margin 

 moderately arched, ventral sinuated in front of the middle ; seen from above, ovate. 



