378 Prof. F. M'Coy on new Species of Fossil Volutes 



Voluta antiscalaris (M'Coy). 



Ovate, moderately ventricose, rather abruptly attenuated to- 

 wards the front ; spire moderately acute, apical angle 65° to 70°, 

 of four to five whorls, and a rounded, swollen, smooth, oblique 

 nucleus at the tip, of one turn and a half; body-whorl with 

 about sixteen to twenty-four angular, slightly sigmoid longitu- 

 dinal ribs extending rather less than halfway to the front, narrow 

 and sharp in the young, wider and more obtusely angular in 

 adults, becoming gradually obsolete in front, each ending in a 

 sharp conical tubercle crowning the obtusely angulated shoulder; 

 a second row of smaller, pointed, conical tubercles surmounts the 

 larger on each whorl ; the space between the two rows is deeply 

 concave and rather wider than the interval between the correspond- 

 ing larger tubercles ; the space between the upper row and the 

 suture is flattened, nearly horizontal, and about half as wide as 

 the space between the two rows, both spaces marked only by the 

 coarse lines of growth ; whorls, anterior to the tubercles, crossed 

 by deep, narrow, spiral sulci having flat spaces between them 

 about equal to half the distance of the longitudinal ribs from 

 each other ; usually about three of these spiral striae visible on 

 each of the whorls of the spire, crossing the longitudinal ridges. 

 Pillar-folds slender, widely separated, oblique, three or four, the 

 third (or fourth, where it exists) posterior, abruptly smaller than 

 the two anterior plaits; outer lip thin, smooth. Length of large 

 specimens 2 inches; length of body- whorl -j^, penultimate 

 whorl -iVo > greatest width -i-Vt to -yy-o. A specimen 8 lines long 

 gives all the same proportional measurements. 



A careful comparison of specimens of the true V. scalaris 

 (Sow.), from the Middle Eocene beds of the Isle of Wight and 

 Barton, will show (what none of the existing figures or descrip- 

 tions would) that our species, which I have named V. antiscalaris, 

 is not identical, but a most remarkable instance of a representa- 

 tive form, distinguished with apparent doubtfulness by a slightly 

 longer spire, less ventricose body, and the ribs less twisted at 

 their anterior end, but with perfect certainty by the spire, which 

 in the European species is sharply pointed (in accordance with 

 the genus Volutilites, Swa.) and of eight or nine gradually and 

 regularly tapering whorls, the apical two or three smooth; while 

 in the Victorian species it terminates in an obtusely rounded, 

 smooth, swollen nucleus or " pullus " of one turn and a half, 

 below which are only five sculptured whorls in adult individuals. 

 In accordance with the slightly more slender form, the pillar is 

 less curved than in the English species, and the plaits slightly 

 thinner and more oblique; the number of ribs in a whorl is 

 greater (being about fourteen or fifteen in the English species); 



