23O PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
than half of the shell (lower end of shell damaged). Upper whorls quite 
high, about two-thirds as high as broad (the measurements are : height of 
penultimate whorl, 24 mm; width, 38 mm). Whorls almost evenly con- 
vex, only slightly appressed and concave toward the suture, without a dis- 
tinct angulation. Surface beautifully cancellated by spiral and longitudi- 
nal ribs. Spiral ribs strongly developed, equidistant, sharp, a little more 
crowded on the upper whorls than on the last one. Longitudinal ribs a 
little stronger than the spiral ribs, sharp, running from suture to suture, 
about 30 on the last whorl. Cancellations rectangular, about twice as 
broad as high on the last whorl, and about three or four times as broad 
on the upper whorls, traversed by fine lines of growth. Mouth elongated 
(lower end not preserved). Columellar plaits not clearly visible, but there 
are at least two which seem to be quite weak. 
Height, 148 mm (not complete); diameter, 65 mm. 
Remarks: The sculpture of this species is quite unique, and charac- 
terizes it sufficiently. Although the sculpture can be compared with that 
of V. triplicata and gracilior to which this species is apparently related, the 
large number of longitudinal ribs, which are developed as sharp and nar- 
row carinae, and the cancellations produced by the stronger development 
of the spiral ribs are quite unlike what we see in the other species named. 
The specific name is given in honor of Mr. O. A. Peterson, Mr. 
Hatcher’s assistant, who collected this species. 
Record of specimens : Mouth of Santa Cruz River, 1 sp. 
159. VOLUTA DORBIGNYANA Philippi. 1 
PI. XXXVI, Fig. I 
1887 V. d. Philippi, Tert. & Quart. Verst. Chiles, p. 70, pi. 7, f. 7. 
1899 ^ d. v. Ihering, in: N. Jahrb. Miner., etc., v. 2, p. 33. 
Shell fusiform. Whorls 6 (and two apical whorls). Spire conical, 
moderately long. Mouth distinctly longer than half of the shell, almost 
two-thirds of it. Whorls convex, with a more or less distinct shoulder, 
above which the upper part of the whorls is depressed or slightly concave 
(more distinctly so on the last whorl), and appressed to the suture. Sur- 
1 It is to be remarked, that there already exists a Voluta orbignyana Mueller (Mon. Aachen. 
Kreideverst., v. 2, 1851, p. 50). The latter species, however, is brought by Holzapfel (Palseon- 
tograph., 34, 1868, p. 97) into the genus Voliitolithes. 
