NO. 1110. PROCEEDINGS OF THE NATIONAL MUSEUM. 3Q9 



on tlie shoulder behind the groove; aperture narrow, the outer lip 

 smoother in front and behind, minutely denticulate near the middle- 

 inner lip thickened; body with two transverse plaits, the posterior 

 smaller ; pillar short, with two oblique plaits, the anterior smaller. Lon. 

 of shell 11, lat. 8.5 mm. 



Pliocene clays of ]Moen, Costa Eica, Gabb; also from Santo Domingo, 

 Bland. This is perhaps the shortest and widest American species. 



MARGINELLA LIMONENSIS, Dall, new species. 

 (Plate XXIX, fig. 12.) 



Shell large, thin, slender, anteriorly attenuated, of about 4 whorls; 

 surface smooth, polished, the spire low, pointed, much obscured by 

 enamel; aperture not quite as long as the shell, narrow, slightly wider 

 in front and behind; outer lip thickened, incurved, smooth, on the out- 

 side, with a shallow sulcus marking off the lip from the whorl behind 

 it; pillar lip hardly callous except near the spire; in front with four 

 subequal obli(]ue plaits, of which the anterior one is coincident with 

 the border of the canal. Lon. 30, lat. 11 mm. 



Pliocene clays of Liuion, Costa Rica, Hill. No. 107076, U.S.N.M. 

 This species recalls M. avtiqua, Redfield, from the newer Miocene of 

 Duplin County, North Carolina, but is smaller, more slender, with pro- 

 portionately more prominent spire. 



MARGINELLA AMINA, Dall, new species. 

 (Plate XXIX, fig. 15.) 



Shell elongated, heavy, somewhat attenuated in front, with about 4 

 whorls; surface smooth, jiolished, spire rather more pointed and distinct 

 than in M. Umonensis, and with less enamel on it; aperture narrow, 

 nearly straight, nearly as long as the shell; not widened behind; outer 

 lip thick and heavy, profusely crenulated from end to end, on the out- 

 side with a very deep profoundly excavated sulcus, except above the 

 shoulder, where there is a thick, callous deposit; pillar lip with a wash 

 of callus, anteriorly with 4 plaits, the i)osterior pair transverse, the 

 anterior oblique, enlarging forward; canal wide, excavated. Lon. 25, 

 lat. 13 mm. 



Potrero, Rio Amina, Santo Domingo, in Oligocene beds, Bland. 

 This species is shorter, broader, and heavier than M. Umonensis, from 

 which it is further distinguished by its strongly crenulated lip and the 

 extremely deep sulcus behind the lip. 



MARGINELLA CONIFORMIS, Sowerby. 



Marginella coniformis, Sowerby, Quart. Jouru. Geol. Soc. London, VI, p. 45, 

 1849. 



Oligocene of Haiti and Santo Domingo, Sowerby and Bland, and 

 of Jamaica, Barrett. No. 113769, U.S.N.M. The most abundant Santo 

 Domingo Marginella is the M. coniformis, not figured by Sowerby, but 



