EEPOET ON THE GASTEROPODA. 121 



Fossil. — From the Later glacial beds of Norway (Sars), and of Scotland (Jeffreys). 



There is but a single slightly weathered specimen of this species in the Challenger collection, 

 and the step from Madeira to lat. 4G° S. is so enormous, that I was glad to have my identification 

 of the specimen confirmed by one who knows the species so well as Dr Gwyn Jeffreys does. It is 

 extremely abundant in Madeira, and careful search will probably supply very many additional localities 

 for its dwelling. 



10. Cyclostrema, Marryat, 1818. 



Species. 



1. Cyclostrema excavatum, n. sp. 2. Cyclostrema sulcatum, n. sp. 



3. Cyclostrema conicum, n. sp.^ 



1. Cyclostrema excavatum, n. sp. (PL VIII. fig. 10). 



Station 24. March 25, 1873. Lat. 18° 38' 30" K, long. 65° 5' 30" W. Off Culebra 

 Island, West Indies. 390 fathoms. Pteropod ooze. 



Shell. — Discoidal, keeled, strong, porcellanous white under a dark-brown epidermis, with 

 an entirely open umbilicus and a small mouth. Sculpture : Longitudinals — there are fine, 

 slight, close lines of growth. Spirals — on the last whorl a little below the suture there is 

 a bluntly angulated keel, which on the previous whorls bisects the space between the sutures ; 

 within this keel a broad shallow furrow reaching to the suture is excavated ; towards the 

 mouth on the base is another very blunt and slighter keel. Colour horny or porcellanous 

 white, covered with a dark yellowishJorown membranaceous epidermis. Spire barely 

 raised, but scalar, and in profile just showing each whorl. Apex not very small, exserted, 

 smooth, consisting of one whorl and a half. Suture broadly and angularly impressed. 

 Whorls 4 in all, of slow increase till the last, which is largish. Mouth a little oblique 

 (i.e., the upper lip projects slightly in front of the basal lip), round, but a little elongated 

 between the keel above and that on the base, at each of which, too, it is subangulated. 

 Outer lip not at all patulous, thin, with a very slight thickening within the mouth. 

 Inner lip thickened, but very short on the body. Umbilicus a wide, open, shallow funnel, 

 exposing every whorl. H. 0'048 in. B. 0-087. Mouth, height 0-03, breadth 0-03. 



2. Cyclostrema sulcatum, n. sp. (PL VIII. fig. 11). 



Station 120. September 9, 1873. Lat, 8° 37' S., long. 34° 28' W. Off Pernambuco. 

 675 fathoms. Red mud. 



Shell.— Depressedly globose, keeled, thin, dead white under a dirty-brown epidermis, 

 with a deep funnel-shaped umbilicus and a large mouth. Sculpture: Longitudinals— 



(ZOOL. CHALL. EXP. fART XLII. — 1885.) Tt 16 



