138 Trans. Acad. Sci. of St. Louis. 
the very obtuse base of the shell, absence of canal and in the 
very small anal sinus situated well behind the peripheral 
carina; one of these genera may be named as follows : — 
Tomopleura Nn. gen. 
In this genus the form is rather slender and elongate, with 
acute many-whorled spire and a small smooth and generally 
paucispiral embryo; the aperture is usually about a third as 
- long as the shell. The whorls have each two larger and _ 
more conspicuous smooth spiral carinae, one just below the 
suture, the other at about the middle and also a few other 
smaller carinae. A moderately concave fasciolar surface, 
bearing the small but deep anal sinus, is situated between the 
two principal carinae. Lines of growth generally coarsely 
incised and very conspicuous, as in Pleuroliria. The species 
are moderate or small in size and rather numerous, those be- 
fore me being labeled P. nivea Phil., the type of the genus, 
pouloensis Jouss., makimonos Jouss. and violacea Hinds. 
Such species as cincta Lamk. and bijubata Reeve, resemble 
typical Tomopleura in general form and sculpture and partic- 
ularly in the obtuse base, absence of beak and form and pos- 
terior position of the anal sinus, but the absence of distinct 
lines of growth, generally acute and substyliform apex and 
some other characters would seem to indicate that they are at 
least subgenerically different. 
Among the generic types which may be considered in many 
respects intermediate between the more typical Pleurotomids 
which precedeand the allies of Surcula to be mentioned below, 
may be cited Scobinella Con. (= Moniliopsis Con., and Zelia 
De Greg.), Hucheilodon Gabb, Glyptotoma n. gen., Sinis- 
trella Meyer, Trypanotoma Coss., Clinura Bell., Cochlespira 
Con. (= Ancistrosyrinz and Candelabrum Dall), Cochlespirop- 
sis n. gen., Protosurcula n. gen., Hosurcula n. gen., Cochle- 
spirella Csy., Microdrilla Csy., Aforia Dall, Antiplanes Dall, 
Bathytoma H. and B., and Megasurcula n. gen. These genera 
are all devoid of true ribbing, as in the preceding typical 
Pleurotomids, but have the spirals less developed. The great 
