MOILTJSCA OF THE ' CHALLENGER ' EXPEDITION. 



715 



tentacles, and though tlic forehead is thickened there and trans- 

 versely wrinkled, there is no veil. The usual fringed membrane 

 extends backwards above the foot-edge to the front of the oper- 

 culum, but bears no th reads. 



Shell. — Low, conical, round, with expanded base, sculptured, 

 solid. Sculpture. The whole shell is cross-hatched by narrow, 

 impressed, intersecting lines, which cross the whorls obliquely and 

 not quite regularly nor uniformly, and which cut the surface into 

 little diamonds resembling shagreen. Colour dirty rusty white. 

 Spire rather low, but conical. Whorls of very rapid increase, ap- 

 parently about G. SutureliwQ^v, scarcely impressed. Mouth very 

 oblique, round, nacreous to the very edge. Outer lip very slightly 

 patulous, sharp on the edge, with a thick nacreous layer bevel- 

 led off to tlie edge above and in front, but on the base turned 

 over and advancing in a rounded pad beyond the lip. Flllar-lip 

 consists of a rounded mass of nacre, backed and above obscured 

 by a considerable porcellanous deposit, which is widely but thinly 

 spread out over the body so as to connect in a continuous sweep 

 the outer and the pillar lips. It is distinctly impressed with the 

 scale-like pattern of the underlying sculpture. Its edge is abrupt 

 and chipped. Operculum thin, flat, highly porcellanous, with a 

 translucent and slightly thinner central area on the outside. 

 On the inside yellow, with many whorls, the nucleus nearly 

 central, the suture well marked, and the last whorl less dis- 

 proportionately large than usual. H. 0-87. B. 1-01<, least 

 0-79. Penultimate whorl 29. Mouth, height 075, breadth 

 0-65. 



The sculpture of this species is very peculiar. In form the 

 shell is not unlike a Diloma, or something between Litorina saxa- 

 tilis and a Natica. In texture the shell is thinner than the 

 thickened lip suggests. The measurements of the mouth are not 

 satisfactory, the outer edge of the pillar-lip being indefinite ; if they 

 be taken within the opening, they would give it as more truly 

 round. The a2)ex is eroded; and the whole aspect of the shell is 

 so weathered that but for the presence of the animal I should 

 have taken it for an old and spoiled specimen. 



3. TunBO (Colloxia) ixdutus, W. 



.St. 2\. Mar. 25, 1873. Culebra Island, St. Thomas, Danish 

 AYest Indies. 390 fms. 4 specimens. 



Shell. — Small, conoidal, high^ whorls tumid, base flattened ; 



