FERUSSACIA, MADEIRA. 281 



Porto Santo: Abundant in some places in the higher moun- 

 tains, chiefly at the summit of Pico de Facho, the type locality. 



Helix ovuliformis LOWE, Trans. Cambr. Philos. Soc., iv, 1831, 

 p. 61, pi. 6, f. 27.Achatina o. LOWE, P. Z. S., 1854, p. 206. 

 PFR., Monogr., ii, 278. Lovea ovuliformis WOLLASTON, Test. 

 Atlant., p. 263, with var. pseudopsis, p. 264. 



This seems to be a variable little species. The typical form, 

 as described and figured by Lowe, has no supraparietal nodule, 

 and the parietal callus is thin. Wollaston defines a var. 

 pseudopsis characterized by having a "corneous sphincter 

 [parietal cord] across its ultimate volution, commencing near 

 the angle of the outer lip and merging (as in the case of the 

 L. cylichna, where, however, it is much more expressed), in an 

 unbroken curve, into the columella. 



This callosity is usually very faint, and often (as in the type 

 from which Mr. Lowe's original diagnosis was compiled) obso- 

 lete; but it is sometimes exceedingly apparent, and occasionally 

 indeed so much developed that it shapes out at its commence- 

 ment (near to the angle of the lip) an abrupt and almost denti- 

 form subvertical process. Examples thus furnished might well 

 be supposed, at first sight, to belong to a separate species, did 

 they not pass into the opposite extreme of form by the closest 

 intermediate gradations. I would, therefore, record this phasis 

 of the shell as the var. B. pseudopsis" ( Wollaston). 



In one of the specimens before me (pi. 39, fig. 23) the parietal 

 callus is very thin, but it bears a stout supraparietal callous 

 nodule. There are 4 whorls, the second disproportionately 

 wide. Length 3.6, diam. 1.75, length of aperture 1.75 mm. 



Other examples (pi. 40, fig. 37) have the same shape, 

 4 whorls, but the entering parietal lamella stands alone on the 

 thin, transparent, parietal callus. Length 3.7, diam. 1.7, 

 aperture 1.75 mm. This is the typical ovuliformis. 



Another form (pi. 40, fig. 36) has the spire more conic and 

 elongate, the last whorl more slender; whorls 4; aperture as 

 in the preceding. Length 3.8, diam. J.7, length of aperture, 

 1.7 mm. 



The columella in this species resembles that of F. leacociana. 

 Half-grown shells have the parietal lamella well developed. 



