CAECIDAE 147 



3.0 mm. in length by i.o 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. floridanuTn, 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 ^jh 



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 heav- 

 ily 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. 



Subgenus iMicraneUum Bartsch 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 At- 

 lantic species in this subgenus. 



Caecum pulcbelhnn Stimpson Beautiful Little Caecum 



Figure 370! 



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 crebrictnctum Carpenter Many-named Caecum 



Figure 37m 



Monterey to Lower California. 



