NO. 2094. M0LLUSK8 OF THE GENUS RI8S0INA—BART8CH. 61 



The specimen has lost the nucleus; the 6 whorls reniainmg measure: 

 Length, 4.5 mm.; diameter, 2mm. 



I have seen nothing in the collection examined that we could refer 

 to this species. 



RISSOINA (Folinia) SIGNAE, new name. 



Plate 31, figs. 1, 4. 



^Rissoa insignis De Folin, Meleagrinicoles, 1867, pp. 48-49, pi. 5, figs. 2 and 3, 

 not Rissoa insigyiis Adams and Reeve, 1850. 



Shell elongate-ovate, white. Nuclear whorls 2, well rounded, 

 smooth; post -nuclear whorls exceedingly, strongly, tabulatedly 

 shouldered at the summit, the axial ribs termmatmg at the angle of 

 the shoulders in strong cusps. Axial ribs 12 upon all the turns, 

 strong, sublamellar. Intercostal spaces about three times as wide as 

 the ribs, crossed by very regular, fine, spiral striations. Sutures ren- 

 dered deeply channeled by the summit of the whorls and wavy by the 

 strong axial ribs. Periphery well rounded, base somewhat produced, 

 marked by the contmuations of the axial ribs, which become 

 evanescent on the middle and fine spiral striations ; anteriorly at the 

 msertion of the columella a strong fasciole is present. Aperture oval, 

 consisting of almost two openings — one the main portion, the other 

 smaller portion connected with this by a narrow slit. It is really 

 formed by a triangular projection of the strongly callused outer lip 

 and another, equally strong, projecting inward from the strong 

 parietal callus to meet this; columella strongly curved. 



The type, which is said to come from Negrito Island (loc. ?) or 

 Margarita Island, Bay of Panama, measures: Length, 2.2 mm.; 

 diameter, 1.2 mm. 



EXPLANATION OF PLATES. 



The measurement cited after each species is the actual length of the specimen. 



Plate 28. 



Fig. 1. R. gisna, new species, type, 7 mm., p. 41. 



2. R. helena, new species, type, 7.2 mm., p. 44. 



3. jR.favilla, new species, type, 7.1 mm., p. 43. 



4. R. io, new species, type, 9 mm., p. 44. 



5. R. expansa Carpenter, type, 9.1 mm., p. 46. 



6. R. stricta Menke, 8.7 mm., p. 39. 



Plate 29. 



Fig. 1. R. pcninsularis, new sj^ecies, type, 6 mm., p. 46. 



2. R. barthelowi, new species, type, 7 mm., p. 48. 



3. R. townscndi, new species, type, 5.3 mm., p. 48. 



4. R. dina, new species. The fine sculpture on the spire has been omitted. 



Type, 7 mm., p. 45. 



5. R. fords C. B. Adams. The fine sculpture on the spire has been omitted. 



Cotype, 7.5 mm., p. 40. 



6. R.fortis C. B. Adams.' The fine sculpture on the spire has been omitted. 



Cotype, 6 mm., p. 40. 



