54 STROBILOPS, S. G. ENTEROPLAX. 



18. Strobilops boholensis (Gude). PI. 11, figs. 1-4, 7-10. 



Differs from the type {S. trochospira) in being smaller and 

 having a narrower umbilicus. Major diameter 3.25 mm., minor 

 diameter 3 mm., latitude 1.75 mm. The armature is nearly 

 identical, but the palatal folds are connected at their posterior 

 terminations by a very slight transverse sinuous ridge, plainly 

 discernible externally through the shell wall (Gude). 



Philippine Is.: Bohol. Type in Mr. Ponsonby's collection 

 (now contained in that of Bryant Walker). 



Plectopylis trocJiospira var. boholensis Gude, Science Gossip, 

 IV, March, 1898, p. 285, fig. 74. 



In the Ponsonby Collection, now contained in that of Bryant 

 Walker, there are two specimens. No. 62067, one of which, 

 measuring height 1.95, diam. 3.3 mm., barely 6 whorls, I pre- 

 sume to be the type. The slight discrepancy in size — one- 

 twentieth of a millimeter in the diameter, two-tenths in the 

 height — might easily be due to differences in method of meas- 

 uring, especially in the height, where the points measured are 

 far out of alignment. The umbilicus is contained 3i/4 times 

 in the diameter; the ribs are well developed within its open- 

 ing. The two lamellge of the parietal wall slightly exceed half 

 a whorl in length; near the inner ends a low radial callous 

 band connects them. Their edges are serrate, as described 

 below. There are five basal folds, the one nearest the colu- 

 mella small, the second and fourth larger; there is a callous 

 ridge connecting their inner ends. The parietal callus is less 

 raised than in other species of Enteroplax. 



In this form there is no interparietal lamella between and 

 beyond the inner ends of the parietals, such as Gude figured 

 for S. trochospira. If the latter normally has this structure, 

 the Bohol form must be specifically distinct. 



In other lots from Bohol (A. N. S. P. No. 78457 and B. 

 Walker Coll. No. 32117, Sierra Bullones), out of the Quadras 

 collection, the shell is larger (PI. 11, figs. 8, 9, 10). 



Height 2.2, diam. 3.7 mm. 78457. 



Height 2.25, diam. 3.5 mm. 



Height 2.3, diam. 3.6 mm. ' ^^^^'^' 



