234 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



of which variety a is the larger. Bartsch described Rissoina adajiisi with 

 this variety a as the type, giving the length as 6.0 mm. Concerning the 

 type of R. janus he stated^^ that the shell is so worn that it would be 

 impossible to decide whether spiral sculpture may have been present or 

 absent, and that the only thing that will help in the identification is the 

 outline. With but very few exceptions, our specimens, of which 40 

 were dredged off Taboga Island and 25 in Bahia Honda, Panama, 

 differ from the figure and description of the type of Rissoina adamsi in 

 being smaller (with one less whorl) and in having both the axial and 

 spiral sculpture finer. The specimen figured has 3 smooth, well-rounded 

 nuclear whorls and 6 postnuclear whorls. It was dredged off Taboga 

 Island, Panama, and measures: length, 3.8 mm; diameter, 1.6 mm. 



These specimens may be Rissoina janus but Bartsch 's figure of the 

 type indicates fewer axial ribs and a less conical shape. This might be 

 due to the worn condition of the shell. In any case, the differences do 

 not seem to be great enough to warrant the description of a new species. 



Rissoina (Folinia) signae Bartsch 



Plate 20, Fig. 5 



Rissoina (Folinia) signae Bartsch, Proc. U. S. Nat. Mus., vol. 49, July 

 24, 1915, p. 61, pi. 31, figs. 1 and 4. "The type, which is said 

 to come from Negrito Island (loc. ?) or Margarita Island, Bay 

 of Panama"=i?wort insignis De Folin, Les Meleagrinicoles, 

 (Havre), 1867, pp. 48-49, pi. 5, figs. 2 and 3, not Rissoa insignis 

 Adams & Reeve, 1850. 



Hypotype: No. 741 (Calif. Acad. Sci. Paleo. Type Coll.), from 

 Loc. 27,229 (C.A.S.), dredged in from 3 to 9 fms. in Bahia Honda, 

 Panama. L. G. Hertlein collector. 



A single specimen dredged in Bahia Honda, Panama, seems to agree 

 reasonably well with the figure and description given by Bartsch. This 

 is Rissoa insignis De Folin, 1867 (not Adams & Reeve, 1850), and is 

 stated (De Folin, p. 9) to have come from "I'Ocean pacifique" . . . 

 "pechees aux environs des Negritos" or "autour des iles aux Perles, dans 

 la baie de Panama." There has been some question as to whether refer- 

 ence was made to Negritos Island in Panama Bay, or to Negros Island 

 in the Philippines. 



^^ Rissoina janus C. B. Adams, Bartsch, Proc. U. S. Nat. Mus., vol. 49, 

 1915, pp. 60, 61, pi. 32, fig. 8. Panama. 



