224 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



KEY TO THE3 SUBSPECIES OF OPISTHOSIPHON (OPISTHOSIPHON) ALLENI 



Axial riblets closely spaced providentialis 



Axial riblets not closely spaced alleni 



OPISTHOSIPHON (OPISTHOSIPHON) ALLENI PROVIDENTIALIS, new subspecies 



Plate 36, Figure 12 



This subspecies was collected by C. C. Allen in considerable abundance 

 on the Island of New Providence. It is distinguished from Opisthosiphon 

 (Opisthosiphon) alleni alleni by having stronger spiral sculpture and a 

 much larger number of axial ribs. In the type there are 55 axial ribs 

 on the first of the remaining turns, 93 on the second, 123 on the third, 

 and 127 on the last nine-tenths of a turn. Of spiral threads, there are 

 8 on the first and second and 12 on the remaining turns, while the base 

 has 6, and 3 show on the outer edge of the umbilical wall. 



The type (U.S.N.M. No. 536846) comes from Nassau, New Provi- 

 dence. It has 3.9 whorls remaining and measures: Length, 12.0 mm.; 

 greater diameter, 5.3 mm.; lesser diameter, 4.8 mm. 



U.S.N.M. No. 467067 contains 65 topotypes from the same source. 



OPISTHOSIPHON (OPISTHOSIPHON) ALLENI ALLENI, new sabspecies 



Plate 36, Figure 10 



This subspecies was collected by Professor H. F. Wickham on Egg 

 Island, one of the small cays close to Eleuthera, and by C. C. Allen in 

 the region of Current Sound, Eleuthera. It is easily distinguished from 

 Opisthosiphon (Opisthosiphon) alleni providentialis by having weaker 

 spiral sculpture and a much lesser number of axial ribs. Of axial ribs in 

 the type 44 are present on the first, 67 on the second, 79 on the third, 

 and 97 on the last of the remaining turns. The spiral threads on all but 

 the last whorl are quite poorly defined ; the type has 10 between summit 

 and suture ; there are also 6 spiral threads on the base and 2 at the outer 

 edge of the umbilical wall. 



The type (U.S.N.M. No. 536845) has 4 whorls remaining and meas- 

 ures: Length, 10.8 mm.; greater diameter, 5.5 mm.; lesser diameter, 

 4.8 mm. It comes from Egg Island, near Eleuthera. 



U.S.N.M. No. 509943 contains 3 topotypes from the same source. 



U.S.N.M. No. 467155 contains i specimen from the sea chff near 

 Current Sound, Eleuthera. 



OPISTHOSIPHON (OPISTHOSIPHON) MATOBI, new species 



Plate 36, Figure 13 



The type of this species is a dead shell and therefore of whitish 

 coloration. The nuclear whorls are decollated. The postnuclear whorls 

 are strongly rounded, appressed at the summit, and marked by very dis- 

 tantly spaced, retractively slanting axial ribs, of which 44 occur on all 



