CLASS GASTROPODA 
43 
Subgenus Provanna Dali, 1918 
Trichotropis lomana Dali, 1918 
Proceedings of the Biological Society of Washington, 31:7. 
Shell thin, white under a dull smooth olive-green periostracum, decol¬ 
late but indicating more than three whorls; suture deep but not channeled, 
whorls well-rounded; axial sculpture on the last whorl of about twenty 
slightly arcuate ribs, with subequal interspaces, ceasing abruptly at the 
periphery; on the preceding whorls these extend from suture to suture; on 
the base the axial sculpture is reduced to inconspicuous incremental lines; 
spiral sculpture, behind the periphery, of obscure close-set threads only 
visible in the interspaces; in front of the periphery and between it and 
the canal are four or five strong cords with narrow deep interspaces, 
slightly crenulating the thin anterior margin of the outer lip; aperture 
rounded, throat white, showing the impress of the external sculpture; 
body and inner lip with a thin white layer of callus; pillar arcuate, angu- 
late at the extremity; canal very short and rather wide. Length of (decol¬ 
late) two and a half whorls, 7.0; of last whorl, 6.0; of aperture, 4.0; 
diameter, 5.5 mm. (Dali.) 
Type in United States National Museum, No. 209112. Type locality, 
U.S. Bureau of Fisheries Station 4354, off Point Loma, San Diego, Cali¬ 
fornia, in 650 fathoms. 
Range. Known only from type locality. 
Family CAECIDAE 
Genus CAECUM Fleming, 1817 
Journal of the Washington Academy of Science, 10. 1920. 
Surface of adult shell marked by numerous axial annulations. Oper¬ 
culum thin, corneous, concave. (Bartsch.) 
Range. San Diego, California. 
Five species are known living on our Pacific shores north of San Diego, 
California. 
Type. • Dentalvum trachea Montagu. 
Caecum californicum Dali, 1885 
Proceedings of the United States National Museum, 8:541. Supplementary Report, 
British Association for the Advancement of Science, 655. 
New name for Caecum cooperi Carpenter, 1864; not C. cooperi Smith, 
1862. 
Shell small with 30-40 sharp narrow rings. (Carpenter.) 
[ 645 ] 
