104 GASTEROPODA OF THE INFERIOR OOLITE. 



(fig. 3 h) ; then comes a whorl with a keel nearly median and finely crenulated ; each 

 of these whorls presents a fine basal rim just above the suture. The four or five 

 remaining whorls, including the body-whorl, have the keel almost at the anterior 

 extremity ; traces of the fine crenulation are seen on the keels of the two higher 

 whorls, but this is almost obliterated on the penultimate and body-whorl. In the 

 four or five last whorls there are two fine spiral lines above the keel, and one 

 below ; these are decussated by numerous fine radial lines, often indistinct. The 

 four or five last whorls also develop a continuous chain of bilateral varices (fig. 3 e), 

 each of which sends out a spine on crossing the keel (not always visible). 



Aperture subovate, elongate ; canal very long and straight. Without wing, 

 except so far as the antero-lateral spine, originating in the varix, and not in the 

 outer lip, represents one. 



Relations and Distribution. — This species is extremely variable, especially as to 

 the position of the keel in the anterior whorls. Occasionally the body-whorl is 

 more angular, and in such cases specimens are not always to be distinguished from 

 Sp. didactyla. Indeed, it is possible that Sp. trinitatis represents an incomplete 

 stage of that very bizarre form. 



Somewhat rare in the Sowerbyi-hed of Bradford Abbas, and quoted also from 

 Dundry. 



23. Shnigera longispjna, Deslongchamps, 1842. Plate III, figs. 4a, 4b, 4 e. 



1842. Banella longispina, Desl. Mem. Soc. Linn. Norm., vol. vii, p. 152, 



pi. xi, fig. 29. 



Bibliography. — This being the type of the genus, most forms of Spinigera 

 hitherto found in the British Oolites have been thus referred to by collectors. 

 Deslongchamps' species is, however, in reality almost unknown in our collections, 

 and unless great pains be taken to show the spines it has so much the appearance of 

 an Maria that few would suspect its real nature. 



Description : 



Length . . . . .35 mm. 



Ratio of minor to major axis of width . . 80 : 100 



Shell elongate, fusiform. Whorls subventricose and only slightly compressed. 

 Apical whorls subglobular ; next succeeds an intermediate whorl, subangular, with 

 a median keel, and traces of axial costse anteriorly ; the remaining six whorls, 

 including the body- whorl, have the keel less and less median until its position is 

 at about the lower third. The ornaments consist of numerous spiral lines, which have 

 moderately wide interspaces, and are carried over the bilateral varices in undu- 



