60 STROBILOPS. 



Strohilops lahyrinthica Say, Dall, Proe. Cal, Acad, Sci, (4), 



vol. 15, No. 15, 1926, p. 480. ? Strobilops strebeli Pfeiffer, 



Dall, I. c. 



This species differs from S. lahyrinthica (Say) by the 

 smaller number of basal folds and absence of any above the 

 periphery of the cavity, among other differences. It is closely 

 related to ^S*. strebeli and 8. aenea. The former has a smaller 

 umbilicus, and both differ from ;S^. hannai by the strong de- 

 velopment of the outer basal fold, which is very weak in the 

 Socorro Island form. S. strebeli guatemalensis, which re- 

 sembles S. hannai by its angular periphery, has a far smaller 

 umbilicus, contained about 10 times in the diameter. 



It is named for Dr. G. D. Hanna, who collected! the 

 specimens. 



I have not seen the single specimen which Dall identified 

 as 8. strebeli, but I suspect that it wiU prove to belong to the 

 present species. DaU apparently did not open the shells for 

 examination of the internal armature. 



Strobilops strebeli guatemalensis Hinkley. Page 35, 

 2d line. 



The dimensions of the type should be : Height 1.4 mm., diam. 

 2.4 mm. 



Section Coelostrobilops, n. sect. 



Conic strobilops with broadly open umbilicus, contained 3 

 to 4 times in the diameter. Type 8. wenziana. 

 Strobilops salvini (Tristr.), p. 37, belongs to this group. 



22. Strobilops wenziana Pilsbry. Plate 13, figs. 1-7. 



The shell is conic with blunt apex, nearly straight lateral 

 outlines and rounded periphery, below which it is flattened 

 between periphery and the strong basal convexity around the 

 umbilicus; openly umbilicate, the width of umbilicus con- 

 tained nearly three times in that of the shell. There are 6 

 convex whorls, the first two smooth, the rest sculptured with 

 narrow retractive ribs, separated by spaces averaging on the 

 last whorl three times as wide as the ribs. Most of the ribs 



