SCAPHANDER. 251 



sculpture is composed of rows of short or longer punctations or 

 grooves, which do not unite to form a continuous line except close 

 to the columella in front, and here rather as the result of crowding 

 and overlapping ; these short grooves are not punctate at the bottom 

 as in S. lignarius, but are apt to alternate stronger and weaker, and 

 are more close set than in lignarius of the same size. 



Alt. 33, diam. 17'5 mill. ; diam. of aperture 13'5 mill. (Dall). 



West coast of Patagonia, 1050 fms. ; near Galapagos Is., 812 fms. 



S. interruptus DALL, Proc. U. S. Nat. Mus. xii, p. 297, pi. 12, f. 

 12, 1889. 



S. MUNDUS Watson. PL 31, figs. 13, 14. 



Shell obliquely oval, thin, opaque, ivory-white, glossy, stippled in 

 spiral lines, abovre narrowed obliquely, concavely truncated, and on 

 the right bluntly pointed, below rounded. Sculpture : Longitudinals 

 there are very fine hair like lines of growth, with slight irregular 

 interrupted and unequal undulations. Spirals the whole shell is 

 covered with small shallow distant impressed dots: these above are 

 roughly rounded or obliquely longitudinal ; but from about one- 

 third of the way down they become transversely elongated ; they are 

 arranged in rows not quite equal, and which are parted by intervals 

 of fully double the breadth of the dotted rows ; toward the point of 

 the base the dots tend to return to the round shape, and the rows of 

 largish dots are parted by rows of minute transversely elongated 

 dots which occur in the intervals. Besides these, there are over the 

 whole surface the close-set superficial microscopic spiral lines, which 

 seem to be a characteristic of the genus. Epidermis excessively 

 thin, membranaceous, and glossy, of a faint straw colour. Colour 

 ivory-white. Crown oblique. There is a slight indentation or small 

 conical pit almost completely coated with the glaze of the lip ; this 

 little pit is encircled by a very slight and blunt keel. Mouth irreg- 

 ularly pear-shaped, being somewhat narrowed above and expanded 

 below. Outer lip projects a little angularly behind, and here it is 

 reverted, thickened, and appressed ; from the highest point of its rite 

 it sweeps round to the point of the pillar with a very equable curve ; 

 it is very patulous on the base. Inner lip flexuous, being very con- 

 vex on the body and openly concave on the pillar. A very thin 

 glaze extends from the outer lip above across the body to the pillar, 

 which has a pretty strongly reverted rounded and twisted edge, up 

 which one can just see into the interior of the shell for nearly two 



