Lamellariidae 127 



symmetrically rounded to a central, elevated summit where the shell is 

 visible through the semi-transparent mantle. The mantle completely 

 covers the body and the shell, whose apex is seen posteriorly at the 

 right. Structural details of the dark liver are visable through mantle and 

 shell. 



The mantle is grayish, semi-transparent; its free edges are thin 

 and delicate, rounded behind, slightly 'frilled' at the sides where there are 

 three indentations or slits. These slits may be deepened by contraction 

 of the body of the mantle. Directly in front, the mantle has a deep central 

 fissure whose edges are folded and reflected to form a siphonal canal 

 which is directed forward and upward at an angle near 25 degrees. This 

 siphonal canal can be lengthened or shortened and widened. 



The outer surface of the mantle is peppered with small black dots 

 tending to circular grouping and surrounded by numerous granular ap- 

 pearing, refractile, white 'sugar grains'. Less numerous and irregularly 

 placed are clusters of these dots conically elevated above the general 

 surface level. The free edges of the mantle are thickly covered with 

 minute pin dots like fine sugar crystals, slightly refractile, as are those 

 over the body of the mantle. The dots are entirely absent from the mantle's 

 inner surface. Under low magnification the entire surface of the mantle 

 appears finely granular throughout its thickness. Its whole surface is 

 sensitive to touch. 



Lamellaria koto^^s Schwengei PI. 47, fig. 328 



Alt., 16.4 mm.; length, 18 mm. This Lamellaria is similar in 

 shape to Lamellaria leucosphaera but is slightly larger in all measure- 

 ments, the body whorl much less globose and the aperture compara- 

 tively larger. Also the spire is higher, the sutures more deeply im- 

 pressed giving each whorl a more rounded appearance. The shell 

 is a milk-white, instead of clear transparent, and the male animal 

 is milk-white, while the female animal is a dull gray. 



Genus MAKSEXINA Gray, 1852 

 Marsenina globosa"--" L. Perry PI. 24, fig. 169 



Alt. from base of columella, 14; from base of expanded lip, 

 15.5; greatest diam., 14; extreme thickness, 9.25 mm. Shell thin, 

 translucent, milk-white; glossy, diaphanous epidermis; apex and 

 apical whorls small, extremely thin; two small whorls, the second 

 enlarging abruptly into body whorl which constitutes about eight- 

 tenths of the extreme altitude; whorls oblique, convex, inflated; 

 sutures impressed; surface shows only fine incremental lines; aperture 

 wide, obliquely expanded; outer lip thin, sharp; columella incurved, 



--5 Named for Alfred S. Koto. 



2-^ Lat., globosus, globular, spherical. 



