Ventura, California, to Lower California.
2 to 3 inches in length; characterized by a strong, wavy, overhanging periphery, and by the dark-brown, fuzzy periostracum. Base concave, with 3 small, indistinct spiral cords. Outside of operculum with 3 strong, prickly ridges. Common in shallow water, especially around Todos Santos Bay, Lower California.
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Figure 35. Astraea gibberosa Dillwyn, 2 inches. c, outer side of calcareous operculum; d, muscle attachment side.
Subgenus Pachymoma Gray 1850
Figure 35
Vancouver, B. C, to San Diego, California.
11⁄2 to 3 inches in length, heavy, brick-red to reddish brown in color. Characterized by 5 to 6 strong, spiral cords on the flattish base. Operculum chitinous green on inner side; outer side swollen, smooth, enamel-white. Formerly A. inaequalis Martyn. Moderately common just offshore down to 40 fathoms.
Genus Homalopoma Carpenter 1864
Shells small, turbinate in shape. Operculum calcareous, oval, thick; its exterior with a thick, paucispiral whorl. Underside of operculum convex with multispiral, chitinous whorling. Leptothyra Pease 1869 is this genus.
Southeast Florida, Cuba to Yucatan.
