| Home> Cenozoic> Miocene>
 

List species

Calocyclas extensa Clark and Campbell, 1942

Description - Add description

Shell stout and robust, bell-shaped; apical horn conical, narrow, generally spine- or needle-shaped, distally sharp and basally not expanded, but with few short riblets around it, the horn 0.36 total length in length; cephalis conical (42-70), flat-sided, its apex bearing the horn, and its base continued in contour with the thorax, the basal diameter as much as twice the altitude; thorax a basal segment of an apically truncated hemisphere (fig. 10) or a cone (fig. 11, 37) in which instance there is a rounded shoulder about halfway the length of thorax with the sides subparallel in the lower thorax, the lower margin of the thorax limited by a narrow, horizontal, internal septal band, whose diameter is 0.43 total length, the band constricting the lateral contour of the shell only a trifle; abdomen a short cylinder, sometimes with slightly convex sides when it is like a thick wedding-ring, the abdomen 0.31 total length and 0.43 in apertural diameter, the diameter distally being approximately similar; aperture irregular, tending to form subregular, incurved prongs or teeth, often torn and ragged; wall rather thick, hyaline; surface of horn hyaline; of cephalis with scattered, relatively large circular pores; of thorax with subcircular, large pores set into concave areas with strongly blunted, short sepaloid conules; of abdomen with the pores a trifle larger than on the thorax and similarly set, save that the sepaloid points are not so strong. Length of shell, 250; of horn, 87.0; of cephalis, 34.2; of thorax, 51.8; diameter of septal band, 98.0; of pores, 4.4-12.2.
Clark and Campbell 1942


Description

 

Images

 

Synonyms

 

References

 

Distribution

 

Discussion / Comments

 

Web links