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CAECIDAE
147

3.0 mm. in length by 1.0 mm. in diameter, opaque-white, with 20 to 30 strong, axial rings, the last 3 or 4 being quite large.

Caecum cayosense Rehder
Key Caecum

Bonefish Key, Lower Florida Keys.

Shell similar to C. floridanum, but with about 14 very large, sharp axial rings.

Caecum californicum Dall
California Caecum
Figure 37g

Monterey to Lower California.

2.0 to 3.0 mm. in length. With 30 to 40 moderately developed, evenly spaced, rounded or squarish axial rings. Lip of aperture slightly thickened. Color a glossy, olive-brown.

Caecum dalli Bartsch
Dall’s Caecum
Figure 37h

San Diego to Lower California.

About 3 mm. in length, usually with 18 to 24 moderately developed, evenly spaced, rounded or squarish, axial rings. Lip of aperture usually heavily developed in adults. Color tan. The number of raised rings varies from specimen to specimen, often in the same locality, and diligent search will usually bring to light any number desired. Extremes have been unwisely named (15 rings—C. grippi Bartsch; 17 to 19 rings—C. licalum Bartsch, and 19 to 22 rings—C. diegense Bartsch). Figure 37h is the holotype.


SubgenusMicranellumBartsch 1920

Shells 3 to 7 mm. in length, opaque, with numerous, fine, closely packed, axial rings. About 8 Eastern Pacific and perhaps half a dozen Western Atlantic species in this subgenus.

Caecum pulchellum Stimpson
Beautiful Little Caecum
Figure 37d

Cape Cod south to North Carolina.

About 2 mm. in length, translucent-tan and glistening when alive; chalky-white when dead; with about 25 to 30 fine, closely set axial rings. Apex with a dome-shaped plug.

Caecum crebricinctum Carpenter
Many-named Caecum
Figure 37m

Monterey to Lower California.