﻿ANTITROCHUS. 235 



1. Antitrochus arietinds, n. sp. PI. XXIII, figs. 11 — 13. 



1841. Pletjrotomaria antitorquata, Phillips (pars). Pal. Foss., p. 96. 

 1854. Vermetus antitorquatus, Morris (pars). Cat. Brit. Foss., p. 285. 

 1889. Scalaria antiqua, Whidlorne. Geol. Mag., dec. 3, vol. vi, p. 30 (not 



Munster). 



Description. — Shell spiral, moderate in size, sinistral, pyramidical, turbiniform. 

 Spire containing about four regularly and rapidly increasing whorls. Suture 

 very deep, narrow, and horizontal. Sutural angle varying, so that on one side the 

 whorls are horizontal, and on the other very oblique. Whorls very convex, being 

 circular or short-elliptic in section. Ornament reticulate, consisting of about 

 eighteen or twenty rounded, distant, rather unequal, and occasionally slightly 

 undulating spiral lines on the body- whorl (including the base), of which more 

 than half are visible on the upper whorls ; crossed by finer, straight, longitudinal 

 lines, sloping obliquely backwards from the suture. Umbilicus apparently minute, 

 and twisted. Mouth rounded or subquadrate, slightly angulated below. Inner lip 

 thickened, elevated, recurved on itself. 



Size. — Height 18 mm., width 16 mm. 



Localities. — There are four specimens in the Godwin-Austen Collection in the 

 Museum of Practical Geology from Wolborough ; and another specimen in the 

 Battersby Collection in the Torquay Museum, which appears to have come from 

 Lummaton or Barton. 



Remarks. — These shells at first sight appear to agree with Pleurotomaria 

 antitorquata, Phillips, 1 but they differ in the important particular of the total 

 absence of a sinus-band or any deflexion of the longitudinal striae. Those points 

 are very clearly denoted in the enlarged figure which Phillips gives of his shell, as 

 well as in a specimen in the Godwin-Austen Collection, which may have been his 

 type ; and therefore we are forced to believe that the present fossils belong not 

 only to a different species, but also to a different genus. Again, in ScMzo stoma 

 antitorquatum, Munster, 2 with which Phillips identifies his shell as well as in the 

 kindred Schizostoma contrarium, Munster, 3 the presence of a sinus-band situated on 

 the lower part of the whorl is clearly seen ; and therefore it cannot be united to 

 either of these species. At the same time Phillips, while figuring under the name 

 of PI. antitorquata a shell from South Petherwyn, refers to some specimens, 

 belonging to Mr. Godwin-Austen, from Newton. As the present are the only 



1 1841, Phillips, 'Pal. Foss.,' p. 96, pi. xxxvii, figs. 176 d, e. 



2 1840, Munster, ' Beitr.,' pt. 3, p. 87, pi. xv, fig. 12. 



3 Ibid., p. 87, pi. xv, fig. 13. 



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