MADE BY DR. ANTONIO RAIMONDI IN PERU. 281 



Locality. Cerro del Ventanillo, between Pachachaca and Jauja, associated with 

 Ammonites Ventanillensis and Petropoma Peruanus, both of which occur at the 

 Liassic ("?) coal mine of Pariatamba. 



ACTJEONELLA, d'Orb. 

 A. oviFORMis, n. s., PL 40, fig. 6. 



Shell thick, ovate, a little narrower below than above ; spire slightly elevated ; 

 body whorl broadly and regularly convex, narrowing in advance ; aperture narrow 

 above, below broader ; inner lip encrusted and with three large folds in advance, 

 the middle of which is narrowest and highest. Surface smooth ; marked only by 

 lines of growth. 



Locality. From a gray crystalline limestone in the neighborhood of Ollon. 

 Cretaceous. 



Remarks. The species is described from a somewhat imperfect specimen, the 

 fractures of the matrix having crossed the shell also, and broken away parts. The 

 extreme apex is hidden and most of the aperture wanting, though the cross section 

 of the cavity gives its shape. It is nearest in form to A. gigantea, d'Orb., but it 

 has a higher spire and is more convex on the sides and not so acute anteriorly. 



PETROPOMA, N. Gen. 



Shell trochoid ; spire more or less elevated ; umbilicus small or imperforate ; 

 inner lip encrusted on the body whorl and slightly thickened on the umbilical 

 margin, not toothed ; aperture subcircular. Operculum multispiral, subcircular, 

 thick, slightly conical externally and showing the volutions ; internally each volu- 

 tion is expanded on its inner margin so as to cover all the surface except a little 

 central pit. 



The general character of the shell is such that it could, except for the oper- 

 culum, have been referred to the genus Gibhula, perhaps more properly coming 

 into the sub-g-enus Forskdlia of H. and A. Adams, in consequence of the flattened 

 sides to the whorls in the species before us. But like most, if not all the other 

 described Trochoids, that genus is characterized by a horny operculum. In ours 

 it is fully as massive as the shell, and its obliquely truncated margins show that it 

 probably did not possess even a corneous expansion. I have not hesitated in asso- 

 ciating this operculum with the shell, since both are equally abundant in the rock 

 in which they are found, and there is no other shell to which the operculum can 

 be referred. There is no doubt but that many of the species of fossils arbitrarily 

 referred to Trochus and Turbo will have to be separated as soon as sufficient details 

 of their character shall have been obtained. Notable examples of this may be 



