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



Scotland. A species, perhaps distinct from orbicularis, occurs in the Mediterranean. 

 The foregoing description, owing to the unserviceable nature of the Challenger specimens 

 has been drawn up entirely from British and Norwegian specimens, — largely from the 

 published description of G. 0. Sars. Amongst the Challenger dredgings Poly cope orbicu- 

 laris, or some very nearly allied, form has been found as follows : — In mud, brought up by 

 the anchor in Vigo Bay, from a depth of 11 fathoms; off the Cape of Good Hope (?), 

 150 fathoms (Station 142) ; Christmas Harbour, Kerguelen Island, 120 fathoms (?) ; 

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



2. Polycope cingulata, n. sp. (PL XXXV. fig. 7, a-d). 



Carapace, seen from the side, subcircular, length not much exceeding the height, which 

 is greatest in the middle ; the anterior extremity (?) is broader than the posterior ; and, 

 except the middle of the dorsum, which is flattened and nearly straight, the rest of the 

 margin forms one continuous and almost circular curve ; seen from above, the outline is 

 ovate, widest in the middle, the width being equal to two-thirds of the length, lateral 

 margins evenly curved, extremities wide, obtuse, and nearly equal ; the end-view is 

 subovate, widest in the middle, lateral margins regularly convex ; apex broad and deeply 

 emarginate in the middle, ventral margin broadly keeled. The valves are surrounded, 

 except on the dorsal aspect, by a broad, thickened flange or encircling keel, the surface 

 of the shell is perfectly smooth, and marked all over with very minute and closely-set 

 punctures. Length, l-43d of an inch ('575 mm.). 



I have, unfortunately, no record of the locality in which the one specimen of Polycope 

 cingulata was found. 



[PL XXXV. fig. 7, a~d. a Carapace seen left side, b from above, c from below, d 

 from front. All magnified 60 diameters.] 



3. Polycope {}) favus, n. sp. (PL XXXVI. fig. 4, a, b). 



Valves seen laterally irregularly subquadrate, equal in height and length ; anterior 

 margin wide, truncated, not rounded, posterior produced in the middle, where it forms a 

 rounded obtuse angle ; dorsal margin straight, ventral very slightly convex. The shell 

 is bordered throughout by a thickened lip, somewhat as in the preceding species, and the 

 surface is marked by numerous large, deep, and irregular angular pits ; there are also 

 two short, blunt teeth near the postero-ventral angle. Length, 1-5 5th of an inch 

 (•46 mm.). 



One or two valves, belonging, doubtless, to some undescribed species, and perhaps 

 referable to this genus, were dredged in Torres' Straits (Station 185); lat. 10° 35' S., 

 long. 144° 3' K, 155 fathoms. I propose to call these provisionally Polycope favus. 



[PL XXXVI. fig. 4, a, b. a Left valve, seen from side, b the same from above. 

 Magnified 40 diameters.] 



