Vol. 67.] ASSOCIATED ROCKS OF NORTH-EAST MONTGOMERYSHIRE. 453 



Bollia lata (Vanuxem & Hall). 



This species differs only from the type in the horseshoe ridge 

 becoming less marked in the ventral region. 



Krausella arcuata Ulrich. 



Bairdia (Krausella) anticostensis of Jones closely resembles this 

 specimen, but its more acute shape allies it more nearly to Ulrich's 

 species. 



(3) Gasteropoda. 

 Ctclonema donaldi, sp. nov. (PI. XXXVI, figs. 7-9.) 



Shell subcorneal. Height and width approximately equal, about 

 12 millimetres. Apical angle = about 60°. A vertical plane through 

 the apex of the shell would cut it into two unsymmetrical parts, one 

 side sloping at a greater angle than the other. Whorls, four well 

 preserved, with a rudimentary fifth ; nucleus absent. The whorls 

 are convex, with a slight concavity towards the top of each whorl, 

 where it meets the succeeding one. This line of junction is slightly 

 oblique to the horizontal. Revolving ridges or striae absent, but 

 the whorls are marked with fairly strong, oblique, transverse lines 

 about 1 mm. apart, parallel to the margin of the aperture. 



This species is closely allied to Cyclonema sublceve of Ulrich, 1 but 

 the revolving lines present in that species are absent here. The 

 oblique ridges, too, are more strongly developed ; while the slight 

 concavity in the upper part of each whorl also serves to distinguish 

 it. Moreover, the angle of the spire is rather more obtuse. 



Trochus constrictus of M'Coy 2 is very like this species in most 

 respects. It is, however, a larger and more symmetrical form. In 

 M'Coy's species the whorls are nearly horizontal, so that each whorl 

 is almost centrally placed with regard to the succeeding one. 



On these grounds I venture to name the species after Miss Jane 

 Donald (Mrs. G. B. Longstaff), who has done so much research-work 

 upon the Palaeozoic gasteropoda. 



Horizon and locality. — Gaerfawr Grits, Old Quarry, Moel- 

 y-garth Wood. 



Bellerophon (Protowarthia) portlocki, sp. nov. (PI. XXXVI, 

 rigs. 10-12.) 



Height = 27 millimetres ; width at mouth = 20 mm. ; width 

 at the opposite extremity =9 mm. ; breadth =14 mm. 



Shell elongate, elliptical in section about the plane which cuts it 

 symmetrically. Closely coiled, leaving practically no umbilicus. 

 The whorls expand rapidly, until at maturity a fairly abrupt ex- 

 pansion gives rise to a wide aperture, which appears to have been 



1 'Geology of Minnesota' Greol. Nat. Hist. Surv. Minn. vol. iii, pt. 2 (1897) 

 p. 1062 & pi. lxxviii, figs. 48-49. 



2 ' British Palaeozoic Fossils ' 1855, p. 296 & pi. i k, fig. 41. 



