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



3. Cytheritra rucUs{1} G. S. Brady (PL XXXII. fig. 3, a-d). 



Ctjtherura rudis, Brady, Ami. and Mag. K"at. Hist., ser. 4, vol. ii. (1868), p. 34, pi. v. iigs. 15-17. 



Carapace oblong, rather compressed ; seen from the side rhomboidal, greatest height 

 situated near the front and equal to more than half the length ; anterior extremity 

 broad, oblique, only slightly rounded, posterior narrower, oblique, produced near the 

 middle into a very short and broad beak ; dorsal margin sloping backwards with a very- 

 gentle ctirve from the front, ventral slightly sinuated in front; dorsal view elongated, 

 subhexagonal, slightly wider in front than behind, anterior extremity abruptly tapered, 

 obtusely pointed, posterior broad, subtruncate, with a wide central mucro ; end view 

 hexagonal, the dorsal much shorter than the ventral line ; height a little greater than the 

 width. Surface of the shell marked mth polygonal excavations and faint flexuou.s 

 longitudinal ribs, much as in the preceding species. Length, 1-5 2d of an inch 

 {"49 mm.). 



This is rather more angular in contour than the type-specimens which came from 

 Davis' Straits, but in other respects the two entirely agree. The Challenger specimens 

 were got in the Straits of Magellan, 55 fathoms (Station 313). 



[PL XXXIL fig. 3, a-cl. a Carapace seen from left side, h from alcove, c from below 

 d from front. Magnified 60 diameters J 



4. Cytlierura cribrosa, n. sp. (PL XXXIL fig. 5, a^d). 



Carapace, as seen from the side, subquadrate, scarcely higher in front than behind, 

 greatest height situated in the middle, and equal to about two-thirds of the length ; 

 anterior extremity obliquely rounded, posterior produced in the middle into a broad, sub- 

 acute beak ; dorsal margin moderately arched, ventral nearly straight ; seen from above, 

 ovate, widest in the middle, subacuminate in front, mucronate behind, twice as long as 

 broad ; end view subquadrate, height considerably greater than the width. Shell marked 

 over the whole surface with rather large angular excavations. Length, l-45th of an inch 

 (•54 mm.). 



Found only in a dredging from a depth of 160 fathoms. January 13, 1876. 

 (Station 305). 



[PL XXXIL fig. 5, a-d. a Carapace seen from left side, h from above, c from below, 

 d from front. Magnified 50 diameters.] 



5. Cytherura lilljeborgi, n. sp. (PL XXXII. fig. 6, a-d). 



Carapace elongated, compressed, rather higher in front than behind ; seen from the 

 side, subovate, greatest height situated in front of the middle and equal to half the length ; 

 anterior extremity obliquely rounded, and jagged l^elow the middle with three or four 

 small teeth, posterior rather narrower and produced in the middle into a broad truncated 



