MADE BY DR. ANTONIO RAIMONDI IN PERU. 215 



cross sections of the whorl differ markedly, though no specimen, I have seen, of 

 Gibbonianus shows an entire section. Enough, however, is known to show that 

 the umbilical margin is deep, and nearly at right angles to the side of the whorl. 



A. Andii, n. s., PI. 39, fig. 3, 3a, 3b. 



Shell discoidal, very convex in the middle and compressed on the doi'sum ; 

 whorls entirely enveloping ; umbilicus minute, deep ; aperture broadly cordate, 

 deeply emarginate on the ventral side. Surface marked by strong lines of growth, 

 slightly sinuous on the sides and arching strongly forwards close to the dorsum. 

 Besides these, on the dorsal half of the side are obsolete ribs, and near the margin 

 a row of barely perceptible tubercles. Septum consisting of a dorsal and three 

 lateral lobes. The dorsal lobe is large, broader above than below, and ends in a 

 slender branch on each side, bearing one digitation on its inner side and two on 

 the outer; above this, at the base of the lobe, is a long, narrow tridigitate branch. 

 The adjoining saddle is very oblique, and is unequally divided by a large tongue. 

 The superior lateral lobe is small and narrow, ending in an oblique branch bearing 

 three teeth on its lower side and one longer process on the upper; above it, on the 

 body of the lobe, are two processes on the upper side, and one more complex on 

 the lower. The next saddle is oblique, higher on the lower side and indented by 

 three teeth of unequal size. The inferior lateral lobe is small, and is divided into 

 three bidentate branches of nearly equal size. The next saddle, occupying the 

 curved surface adjoining the umbilicus, is nearly straight, divided in the middle 

 by a small tongue, the upper half again subdivided by a smaller tongue. Up to 

 this point the septa continue entirely separate, but the next lobe, lying on thie 

 umbilical face, is very broad, divides into three broad branches, some of the points 

 of which are obliterated by abutting against the last saddle of the preceding 

 septum. 



Measurements. Greatest diameter, 2.5 inches; greatest width of aperture, 2.0 

 in.; greatest width of body whorl, 1.6 in.; height of aperture from the dorsum of 

 the preceding whorl, 1.0 in. 



Locality. " Province of Pataz ; Dept. of Libertad ; height, 3000 metres." 

 Remarks. In his notes, Dr. Eaimondi considers the formation Cretaceous, but 

 we have in this single fossil a sufficient proof of its being Jurassic. The specimens 

 are in a beautiful state of preservation, and come from a light-colored, crystalline 

 limestone showing every detail in perfection. The species belongs to the group of 

 which A. cordatus, Sowerby, is the type. It resembles that shell in external cha- 

 racter to some extent; so much so that I should have probably hesitated in sepa- 

 rating it, had I not possessed the details of the septum. In this, it differs alike 



