Morgan Expeditions. 115 



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 Pleurotomaria, one specimen measuring about 

 8.5 mm in length, and 11 mm 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 JSFuculites Nyssa, Streptorhy nchus Agassizii, etc., 

 in the Devonian sandstone of Erere, 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 well rounded. They increase quite rapidly 

 in size from the very small apex, the last one being ventricose 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 mm ; 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 



