26 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
portion; body with a very thin wash of callus; color of the shell yellowish 
subtranslucent white. Length of shell, 8; of aperture, 7.25; breadth of 
shell, 5 mm. (Dali.) 
Type in United States National Museum, No. 109301. Type locality, 
near Avalon, Catalina Island. 
Range. Catalina Island, in 50 fathoms. 
Genus MICROGLYPHIS Dali, 1902 
This is a group of chiefly deep-water species, characterized by a very 
short spire and globose shell in which the end of the pillar is not only 
truncate as in Rictaxis , but has a marked sulcus behind it and is produced 
laterally into a rather wide spiral flange at maturity, and is concave with 
a single feeble plait behind the terminal laminae. Inoperculate. (Dali.) 
Type. Acte on curtulus Dali. 
Microglyphis breviculus Dali, 1902 
Plate 1, fig. 14 
Proceedings of the United States National Museum, 24:512; Bulletin, Museum of 
Comparative Zoology, 43; PI. 15, fig. 12. 
Shell small, short, plump, yellowish-white, with four and a half polished 
whorls; nucleus sinistral but wholly immersed, so that the apex seems as 
if dextral, smooth; whorls convex, rapidly increasing, separated by a 
deep, almost channeled, very narrow suture; sculpture of extremely faint, 
fine spiral striae almost absent in front of the suture and growing more 
distinct anteriorly, not visibly punctate; aperture ample, outer lip simple, 
body with a well-marked callus, continued on to the pillar and spreading 
a little over the base behind the pillar, which is concavely arcuate, its 
anterior edge thickened and expanded into a strong spiral plait or lamina 
behind which on the pillar is a second less-marked plait; in front of the 
pillar is a small but distinct notch. Length, 3.6; max. diameter, 2.25 mm. 
(Dali.) 
Type in United States National Museum. Type locality, off Santa 
Rosa Island, United States Fish Commission Station 2902. 
Range. Monterey, California, to Point San Quentin, Lower Cali¬ 
fornia. 
Microglyphis estuarinus Dali, 1908 
Bulletin , Museum of Comparative Zoology, 43, No. 6, p. 238. 
Shell small, white, plump, with a very short, rather acute spire, and a 
swollen last whorl; there are four and a half closely-coiled whorls, the 
[26] 
