STROBILOPS. 



59 



species, such as 8. texasiana. It differs from that species by 

 the weaker ribs and wider umbilicus among other features. 



I obtained no living specimens of this little snail, and indeed 

 did not see it in the field. Three entire and three broken 

 examples were found in leaf debris gathered on the ridge 

 running north from High Peak. {Piratica, belonging to 

 pirates — who used this island as a base after Morgan wrested 

 it from the Spaniards.) 

 21. Strobilops hannai, new species. PI. 16, figs. 3, 3a, 4. 



The shell has a dome-shaped spire of closely coiled, moder- 

 ately convex whorls, a bluntly but distinctly angular periphery 

 and moderately convex base. Umbilicus contained about 614 

 times in the diameter. Color deep olive-buff, rather dull 

 above, glossy at the base. Sculpture: the first 11/2 whorls 

 smooth, the rest with retractive ribs about half as wide as 

 their intervals. Most of these ribs disappear after passing 

 over the periphery, but some continue diminished over part 

 of the base, and a few weakly to the umbilicus. The aperture 

 is lunate, oblique. Lip is white, moderately expanded, thick- 

 ened within. The parietal callus is thick. The parietal 

 lamella is strong, emerges to the edge of the callus, and 

 penetrates half a turn. Infraparietal lamella also penetrates 

 as deeply as the parietal, is rather high at the inner end but 

 weakens further forward, not emerging in the aperture. Both 

 of these lamellae have strong nodes which are profusely, shortly 

 spinose. There is a low interparietal lamella between the 

 inner ends of the large lamellge. There appears to be no 

 columellar lamella. Basal folds three: the inner or fold 1 is 

 well developed but short; fold 2 is larger; the third fold is 

 very small and thin (it apparently represents either No. 4 

 or 5 of the diagram on page 2 ; in a second specimen it could 

 not be seen, but possibly was broken away in opening the 

 shell). 



Height 1.7, diam. 2.4 mm. ; 5i/^ whorls. Type. 



Height 1.5, diam. 2.2 mm; 5i/^ whorls. 



Socorro Island, off western Mexico, at 2000 feet (G. D. 

 Hanna). 



