115 Morgan Expeditions. 
sides. Height less than the breadth; spire very depressed-conical; api- 
cal angle somewhat greater than a right angle. Volutions about three 
in number, the last angular and carinate along the middle, with the upper 
surface flattened, or curving very slightly from the suture to the median 
carina. The upper surfaces of all the volutions, from the apex to the 
carina of last volution, lie in nearly the same plane and are separated by 
a shallow suture; lower side of the body volution slightly more convex 
than the upper. “Aperture and surface markings not preserved. This is 
a very small species of Plewrotomaria, one specimen measuring about 
8.5 ™™ jn length, and 11 ™™ in breadth. 
Only a few specimens of this species have been obtained, 
and none of these are in a very perfect condition. Asso- 
ciated with Nuculites Nyssa, Streptorhynchus Agassizit, ete., 
in the Devonian sandstone of Ereré, Prov. of Para, Brazil. 
Named in honor of Tenente Rocha, commandant of the 
Marine Arsenal at Para, to whom the expedition of 1870 
was indebted for the fitting out of the steamer Jurupensem. 
Genus HOLOPEA, Hall. 
Holopea Furmaniana, sp. nov. 
Shell rather above the medium size, obliquely sub-conical in front view, 
with the length and breadth nearly equal. Volutions about three or four 
in number, very prominent and wellrounded. They increase quite rapidly 
in size from the very small apex, the last one being vertricose and some- 
times slightly flattened on the top near the suture, which is rather deep 
and acute-angular. Aperture slightly oblique, oval in outline and a little 
reflected on the lower side. Surface, as determined by external moulds, 
smooth. One specimen of average size measures: length and breadth 
each, about 17 ™™; but many specimens are larger than this. : 
All the specimens of this form, so far obtained, are in the 
condition of moulds of the interior and exterior. In the in- 
ternal mould there is a small umbilicus, probably due entirely 
to the removal of the columella. This form is easily recog- 
nized by its regular and well rounded volutions and low 
spire, the volutions commencing of very small size and in- 
creasing rapidly and regularly to the aperture. So far as we 
are aware the genus Holopea has not been recognized from 
the Devonian before; but the smooth exterior of this form 
