MOLLTISCA OF THE ' CHALLENGES ' EXPEDITION". 249 



baving any definite view of its true place. Mr. Adams considers 

 it most nearly connected with Rissoa (subgen. Alvania) ; but his 

 description of the animal does not justify this estimate; and, so 

 far as I am aware, its true place is undetermined. 



Fenella. elongata, n. sp. 



St. 24. March 25, 1873. Lat. 18° 38 r 30" N., long. 65° 5' 30" 

 "W. Culebra Island, St. Thomas, West Indies. 390 fins. Coral- 

 mud. 



St. 78. July 10, 1873. Lat. 37° 24' N"., long. 25° 13' W. Off 

 San Miguel, Azores. 1000 fms. Gloligerina-ooze. 



Shell. — Small, high, narrow, conical, with deep wide sutures 

 and rounded whorls and base, translucent white. Sculpture. 

 Lougitudinals — on the last whorl there are 12-13 narrow and 

 sharply-rounded, but not high, ribs, parted by furrows about four 

 times their width ; they cross the whorls with a slight sinistral ob- 

 liquity, and are abruptly interrupted on the last whorl by the edge 

 of a basal tabulation, where the entire base is levelled up beyond 

 the summit of the ribs, which thus all but disappear. On the 

 earlier whorls the ribs are rather fewer in number, and are some- 

 what closer set ; on the third they are crowded, on the second and 

 first they are absent. There are besides these very numerous, 

 close-set, rounded, microscopic threads on the lines of growth ; 

 these, as usual, are most distinct on the base. Spirals — there 

 are on each whorl three very narrow rather prominent threads, 

 which rise into tubercles in crossing the longitudinal ribs. The 

 highest, which is the strongest, is about two fifths of the whorl's 

 height below the suture, the costal tubercles on it are sharp and 

 prominent, and it forms a distinct though not strong carina ; on 

 the last whorl the edge of the basal tabulation, which exactly 

 meets the outer lip, forms a fourth thread, and between all the 

 spirals there is a faint trace of one intermediate, like a shadow ; 

 on the tabulation of the base there are three or four very feeble 

 and faint rounded threads. Colour glossy, transparent white. 

 Spire very high and narrow, perfectly conical, but having its out- 

 lines broken by the strong sutural contractions which constrict 

 the top and bottom of each whorl. Apex small and regularly 

 attenuated, but blunt and quite round, the extreme end being 

 slightly impressed. Whorls 12J, of very gradual and regular in- 

 crease, with a sloping shoulder below the suture, roundly bulging 

 and slightly contracted into the suture below : the projection of the 



