NERINyEA. 219 



The section of the type is unknown ; a specimen from the Pea-grit of 

 Longfords, showing the posterior half (fig. 9 c), gives indications of a structure on 

 the bacillus or Oppelensis plan. A section of the anterior half (fig. 9 h) gives faint 

 indications of a similar character. 



Relations and Distribution. — Owing to the fact that the two portions of this 

 very dimorphous form are rarely found in one piece, a degree of uncertainty hangs 

 about the species. Posteriorly its relations with Pti/g. bacillus are intimate, but 

 the anterior portion is quite different. From Pti/g. Oppelensis it is separated by 

 the height of the whorls and by its more elongate habit. 



Rare in the Freestone, Nails worth, and in the Pea-grit at Longfords. 



A specimen from the Lincolnshire Limestone of Wakerly (figs. 8 a and 8 /;), 

 which I temporarily designate as PtygmaMs " baccilloides,^^ reminds us of the pos- 

 terior portion of Ptyg. JonesH, though the whorls are a little shorter. 



The section of the "Wakerly fossil seems to be on the bacillus-Oppelensis plan, 

 but it possesses considerable peculiarities of its own, which at present require the 

 confirmation of other specimens. 



155. NBRiNiEA (Ptygmatis) Oppelensis, Lycett, 1857. Plate XV, figs. 11 a — e. 



1857. Nehin^a Oppelensis, Lycett. Cotteswold Hills, p. 123, pi. ii, figa. 6, 



1887. _ — _ Witchell, vol. cit., p. 30, pi. i, fig. 3, 3 a. 



Bibliography, Sfc. — Originally described from a fragment found in the Oolite 

 Marl of Selsley Hill. Witchell considered the section shown by Lycett to have 

 been much worn. Accordingly he substituted another, which is again figured 

 (fig. 11 e). This figure, he says, occurs with slight variations in four Inferior 

 Oolite species. This number may be increased. 

 Description : 



Spiral angle (mean) . . . .6°. 



Height of whorl to width . . . 1 : 1*4. 



Approximate length . . . .80 mm. 



Shell conical to cylindrical, dimorphous. The spire has a bluntish apex, and 

 the apical angle is nearly double the mean spiral angle, so that the general angle 

 is very obtuse. Whorls twenty-five and upwards, short, with indications of spiral 

 ornament in the earlier stages. The apical whorls are deeply excavated, the spiral 

 belt being thick and prominent. These features gradually soften down until we 

 reach the stage described by Lycett, where the whorls are " slightly tumid at the 

 junctions," and the excavation is but slight. In specimens from the marly Lime- 



