34 STROBILOPS, MEXICO, CENTRAL AMERICA. 



Height 1.65, diam. 2.5 mm. Umbilicus slightly more than 

 11 times in diameter. 



Height 1.6, diam. 2.4 mm. Umbilicus 11 times in diameter. 



Strebel's figures are reproduced in pi. 4, fig. 5. Pfeiffer's 

 description and figures appear to have been from a specimen 

 scarcely mature. The small umbilicus is contained about 11 

 to 12 times in the diameter. The rather strong ribs pass over 

 the very bluntly subangular periphery, but then gradually 

 disappear, leaving the greater part of the base merely striate ; 

 but under a high power, some specimens show faint traces of 

 fine, close, weak spiral striae. The shell is rather strong, 

 opaque and cinnamon-brown, the slightly expanded and thick- 

 ened lip of the same color. There is a slight spiral groove in 

 the latter part of the last whorl, just outside of the umbilical 

 suture. The white parietal lamella is high near its anterior 

 termination, penetrates inward exactly half of a whorl; 

 towards the inner end its edge shows strong nodes which are 

 roughened by microscopic, rather blunt asperities. The infra- 

 parietal lamella is visible in a basal view but does not emerge 

 to the edge of the parietal callus; it penetrates as far inward 

 as the parietal; between them, near the inner ends, is a very- 

 low, nodose interparietal lamella. There is a low columellar 

 lamella and three basal folds, that near the axis short. (In 

 one specimen, pi. 5, fig. 2, there seems to be two short and 

 two longer folds, seen faintly through the base, but the indi- 

 cations of folds are so weak in this shell that the appearance 

 drawn is not trustworthy; its visibility was exaggerated by 

 the draughtsman). 



Height 1.8, diam. 2.6 mm. ; 5i/4 whorls. 



Height 1.8, diam. 2.4 mm. ; 5 whorls. 



5a. Strohilops strebeli guatemalensis Hinkley. PI. 5, figs. 5, 

 6, 7, 8. 



The shell is more sharply ayigular at the periphery than 8. 

 stredeli, with a somewhat smoother base, microscopically stri- 

 ate spirally, and a less thickened lip. The width of the um- 

 bilicus is contained about 10 times in the diameter of the 

 shell. There are three basal folds. 



