MOLLUSCA OF THE ' CHALLENGER ' EXPEDITION. 



703 



sculpture is still very obviously diflerent, and tlie form is globose, 

 not, as in that species, liigli and conical. * 



8. Trocuus (IMaegaeita) lima, W. 



St. 73. June 30, 1873. Lat. 38° 30' N., long. 31° 14' W. W. o£ 

 Azores. 1000 fms. Gloligerina-ooze. 5 specimens (1 full-grown). 



St. 75. July 2, 1873. Lat. 38° 37' N., long. 28° 30' W. Fayal, 

 Azores. 450 fms. Sand. 4 S2)eeimens, in spirit. 



St. 78. July 10, 1873. Lat. 37^ 24' N., long. 25° 13' AV. St. 

 Miguel, Azores. 1000 fms. Glohigerina-oozQ. 7 specimens (3 

 full-grown). 



Shell. — Conical, with a broad and tumid base and a wide nar- 

 rowed umbilicus ; surface cross-hatched like a file ; when fresh, 

 translucent with a pearly sbeen. Sculpture. Spirals — three to five 

 slightly raised remotely beaded threads, of which one lies a little 

 below the suture, one at the periphery forming a carina, of 

 which the beads are much smaller and closer set, sometimes 

 evanescent ; one, with beads like the first, defines the umbilicus, 

 within which there is a strong spiral ridge ; and the whole surface 

 is covered with fine rather sharp threads, whose partings are 

 twice as broad as themselves. Of these finer spirals the one 

 which meets the outer lip often rises into prominence and defines 

 the base, while another above the carina sometimes stands out 

 more strongly and more beaded than the rest. Longitudinals — 

 the whole surface is close-set with these, which are crossed by 

 the spirals, than which they are broader but less sharp, closer- 

 set, and more irregular and interrupted, especially near the upper 

 line of tubercles and near the umbilicus. Colour a bluish white 

 when alive, with a translucent calcareous layer through which 

 the nacre shines. Spire high, a little scalar. Apex small, a little 

 flattened, with the embryonic 1\ whorl barely projecting in 

 the middle. Whorls G-7 ; the last is of rapid increase^ full 

 rounded and a little tumid; the preceding ones are a little 

 roundedly shouldered below the suture, flat on the contour, 

 angulated at the carina, and slightly contracted into the suture ; 

 the apical whorls are simply rounded and longitudinally ribbed. 

 Suture is linear, but strongly, not acutely defined by the p'erpen- 

 dicular rise of the whorl above it and the slight sloping shoulder 

 below. Mouth round, scarcely oblique, with a translucent por- 

 ccllanous edge, and pearly within. Outer lip not descending, 

 sharp, its inner edge is bevelled outwards at the expense of the 



