NO. 12W. ILL USTRA TIONS OF AMERICAN SHELLS— DA LL. 513 
family of gastropods it .should be assigned. As it was dredged at a 
considerable depth there seems no reason to doubt it is normally 
marine. 
TOLEDONIA PERPLEXA, new species. 
Shell small, whitish, smooth, except for faint incremental lines; 
suture distinct, whorls plump and rounded, the last comprising nearly 
the whole shell; nucleus smooth, polished, plump, dextral, of a single 
whorl; subsequent whorls three, smooth, inHated, slightly shouldered, 
with a distinct but not channeled suture; last whorl much the largest, 
surface slightly marked by incremental lines, not polished; periostra- 
cum, if any. lost; aperture ample, outer lip thin, simple, rounded in 
front and passing insensibly into the slightly oblique but not twisted 
pillar, with a thin callus on the body and over the imperforate umbili- 
cal region; plait thin, prominent, but not sharp, situated near the base 
of the pillar and apparentl}^ continued into the coil of the shell; alt. of 
shell 3.2; of aperture 2.2; max. diam. of shell 2.3 mm. 
Dredged in the Straits of Magellan, east of Punta Arenas, ])y the 
U. S. Fish Commission steamer Albatross at station 2778, in 01 fathoms; 
bottom temperature 48° F. U.S.N.M., 109022. 
The most striking features of this puzzling shell are its Succinea- 
like form and its untruncate straight pillar with a single prominent 
plait. 
Genus PLEUROTOMA Lamarck. 
Section ANTIPLANES Dall. 
Among the deeper water and abyssal forms of this genus are some 
which do not seem to fit into any of the hitherto proposed sections. 
These forms are smooth except for incremental lines and sometimes 
fine spiral striae, the periostracum is conspicuous and the shell dis- 
posed to be chalky, the anal sulcus shallow and more or less rounded, 
usually situated some distance from the suture, but not quite on the 
periphery of the whorl, the canal rather wide and long and often a 
little recurved, the aperture unarmed. There are both dextral and 
sinistral species, and 1 propose for them the sectional name of Auti- 
j)lants. The t^'pical species will be Suroula perversa Gabb, of the 
California Tertiary and recent faunas. 
PLEUROTOMA (ANTIPLANES) PERVERSA Gabb. 
Plate XXXIV, fig. 8. 
Pleurotoma perversa Gabb, Proc. Cal. Acad. Sci., Ill, 1865, p. 183. 
Drillia perversa Gabb, Paleont. Gala., II, 1866, p. 6, pi. i, fig. 10. 
Off San Pedro in 60 fathoms. Cooper ; off Lower California in 48 
fathoms, nuid, U. S. Fish Commission steamer Alhafross, at station 
21)34. The latter is figured here. Also in Pliocene and Pleistocene 
shell beds of San Pedro and San Diego, California. U. S. N. M. , 122561. 
Proc. N. M. vol. xxiv— 01 33 
