Original description of Harpagodes americanus by Imlay, 1940:
- ”subfusiform; spire short, probably composed of four whorls, but only two preserved, apical angle about 45 degrees; body whorl very large, forming about three-fourths of the total height. Side of whorls gently convex, suture moderately impressed. Posterior part of body whorl ornamented with many small spiral ribs separated by somewhat wider interspaces. Toward the anterior part of the body whorl four of these ribs develop into prominent, diverging carinae of which the two in the middle are the largest. The carinae are separated by broad, nearly flat interspaces which are marked by weak spiral ribs that increase in number anteriorly. Between the posterior carina and the suture are two spiral ribs of which the most posterior is much larger than the other and about one-third the size of the posterior carina. The anterior carinae curve anteriorly; the posterior carinae curve posteriorly; the posterior-most carina rests against the side of the spire. Anterior canal broken.”
Locus typicus: Barril viejo, Coahuila State, Mexico
Stratum typicum: Barril viejo shale Member, Hauterivian, lower Cretaceous
Dimensions: Height holotype (incomplete) 120 mm.; maximum diameter 110 mm.
Holotype: Museum of Paleontology, University of Michigan no. 20413.
Original comment by Imlay, 1940:
- This species may be distinguished from H. mexicanus Imlay by its shorter spire, relatively larger body chamber, and by the presence of minor ribs between the large carinae. It greatly resembles H. desori (Pictet et Campich) from the Neocomian of Europe, but its carinae are broader and rounder. This species is represented by one internal mold.