130 Trans. Acad. Sci. of St. Louis. 



surface polished and the lines of growth not distinct. The 

 embryo is small, obtuse, smooth and paucispiral, consisting 

 of about a single whorl. Pleuroto7na is represented by a 

 moderate number of species confined to the Indo-Pacific region, 

 such as babylonia Linn., crispa Lamk., grandis Gray and 

 garnonsi of Reeve, and is a recent development, not occur- 

 ring, as far as known to me, in the fossil state. It probably 

 exists, however, in the unexplored upper Tertiaries of those 

 regions. 



Lophiotoma n. gen. 



Although having the small smooth embryo of a single 

 whorl, polished surface and obsolete lines of growth, charac- 

 terizing Pleurotoma, this genus may be recognized at once 

 by the relatively shorter and stouter form as a rule, less 

 elongate and straighter beak, which is strongly tapering in cer- 

 tain large forms like w?iecZo, finer, more acutely elevated and less 

 close-set spiral carinae, with a usually distinct and even, finely 

 lineolate concavity from the peripheral carina to the suture or 

 subsutural collar, the latter being generally present and by 

 the deep anal sinus formed centrally on, and not behind, the 

 peripheral carina, the latter being more strongly elevated and 

 usually subduplex. The genus is exclusively recent, com- 

 posed of large species inhabiting the Indo-Pacific region and 

 is represented in my cabinet by tigrina,virgo and marmorata 

 Lamk., unedo Val., /^c^'e/^ Weink., leucofrojns A. et R. and 

 the following : — 



General form and ornamentition similar to tigrina but more slender, the 

 dark brown spots very minute aud sparse, but similarly distributed, the 

 duplex peripheral carina more strongly elevated and the anal sinus deeper 

 and narrower. Length of a specimen having 12 body whorls, 59 mm.; 

 width, 13 mm. Cebu, Philippine Islands inicrostlcta n. sp 



Pleiiroliria De Greg. 



This genus, originating in the middle Eocene and coming 

 down to the present time, is the American homologue of 

 Lophiotoma, but is composed of much smaller species having 

 a slender form, very characteristic sculpture of two to three 

 strong spiral carinae, the peripheral bearing the small anal 



