﻿570 MISS J. DONALD ON GASTEKOPODA FROM [Aug. I905, 



periphery where the band is situated, somewhat flattened both 

 above and below. Band situated near the middle of the body- 

 whorl, but considerably below the middle on the earlier whorls, 

 concave, and bounded on each side by a strong keel. Ornamentation 

 consisting of four strong threads below the band on the body-whorl, 

 not seen on the earlier whorls ; two fine threads on the upper part, 

 one immediately below the suture, and the other midway between 

 it and the band. Lines of growth strong, raised threads occurring 

 on the upper part of the whorl, almost crenulating the uppermost 

 thread, curving obliquely back to the band, not clearly visible on 

 the rest of the surface, apparently curving forward below the band 

 on the penultimate whorl. Aperture unknown. 



Remarks and Resemblances. — There are three specimens 

 of this species, one of which is very small. The structure is not 

 well enough preserved to permit of its being referred with certainty 

 to any of the subdivisions of Pleurotomaria, but it appears to come 

 nearer to Bembexia, GEhlert, than to any other genus. I therefore 

 place it here provisionally. This species somewhat resembles 

 Pleurotomaria crenulata, M'Coy, 1 but differs in having the base 

 more produced and ornamented by four raised threads. This 

 ornamentation also distinguishes it from PI. Hindei, Lindstrom, 2 

 to which it bears a resemblance in form and in the character of 

 the band. It differs from small specimens of Pleurotomaria Lloydii, 

 Sow., by not having so many strong raised threads above the band, 

 by the upper thread being almost crenulated, by the form of the 

 lines of growth, and by the band being wider in proportion. 



Dimension s. — Length = 4-5 millimetres ; width of penultimate 

 whorl = 2-5 mm. ; height of body-whorl = 2-5 mm. 



Horizon. — (63) Lower Ludlow, Aymestry Limestone included. 



Eembexia (?) sp. nov. (PI. XXXVII, fig. 5.) 



A fragment of the upper part of a shell is partly embedded in 

 the matrix, and only shows four and a half whorls. The whorls 

 are slightly angular at the periphery, where the band is situated, 

 and flattened above and below. The band is below the middle of 

 the whorls, and is prominant and flat; it is not well enough pre- 

 served to show whether it was bordered by keels. The surface is 

 smooth, with the exception of a few obscure lines of growth on the 

 fragment of the upper part of the last whorl, which curve backward 

 to the band. 



Remarks and Resemblances. — This species comes near to 

 Pleurotomaria Holmi, Lindstrom, 3 more especially the variety figured 

 in his pi. xix, fig. 17, which is devoid of the ridge below the suture 

 characteristic of the type. It differs, however, in the position of 



1 'Brit. Palseoz. Foss.' 1852, p. 291 & pi. iX, figs. 45-45 a. 



2 ' Silurian Gastropoda & Pteropoda of Gotland ' Kongl. Svensk. Vet.-Akad. 

 Handl. vol. xix (1881-84) No. 6, p. 99 & pi. xix, figs. 15-16. 



3 Ibid. p. 100 & pi. xix, figs. 17-20. 



