270 MISS JAJ^E DONALD ON THE GENERA [^^y 1899, 



examples from these places. Eoemer refers a cast from the Upper 

 Silurian of E-ostock, Nieder-Kunzendorf, and Lerchenborn somewhat 

 doubtfully to this species. A. von Alth ^ and F. Schmidt '^ record it 

 from the Silurian of Podolia ; and the last-named author ^ also 

 mentions its occurrence, under the name of Pleurotomaria articu- 

 lata^ in the Island of Gotland ; Lindstrom, however, thinks that the 

 shell referred to may be the species named by him Murchisonia 

 moniliformis. 



HORMOTOMA ANTIQUA, Sp. nOV. (PI. XXII, fig. 9.) 



Description. — Shell very elongated, turreted. Whorls more 

 than twelve, increasing gradually, smooth, slightly convex, wide in 

 proportion to the height. Sutures deep. Sinual band situated on the 

 lower half of the whorl, near the anterior suture, slightly depressed, 

 limited on each side by a raised thread. Lines of growth strong, 

 sweeping very obliquely backward to the band above, and forward 

 below, indistinct on the band itself. Aperture rounded, rather 

 produced below, inner lip reflected on the body-whorl. Columella 

 nearly straight. 



Eemarks and Eeseniblances. — This species is remarkable 

 for the great obliquity of the lines of growth above the band, and for 

 the low position of the band ; the whorls are also flatter than in the 

 type of the genus. In the former characteristic it resembles 

 H. articulata, and to some extent IT. Griffitlii, but from both it is 

 distinguished by the much lower situation of the band and the great 

 width of the whorls. The position of the band resembles that of 

 H. cingulata, but there the lines of growth above are not so oblique, 

 and the whorls are still less convex. It is most like H. Anna^ 

 Billings, but the band is narrower and rather higher in that species, 

 the lines of growth less oblique, and the whorls not quite so wide. 

 The width of the whorls in H. antiqua is about twice the height. 

 In general form it greatly resembles Ectomaria Nieszkowslii^ but 

 has not its prominent ornamenting keels ; and the lines of growth, 

 though not distinct on the band, as seen above and below, appear 

 to indicate the deep sinus characteristic of Hormotoma. 



Dimension s. — I have seen only one really good specimen of this 

 species; it is in the Geological Survey Collection, Edinburgh Museum, 

 but there are ten worn fragments associated with it, from the 

 same locality, which are possibly identical. The length of the 

 example figured (PI. XXII, fig. 9) is oQ mm., and the width is 

 about 18 mm. 



Horizon and Locality. — Durness Limestone, Sutherland. 



Hormotoma Geayiana, sp. nov, (PI. XXII, fig. 10.) 



Description. — Shell very elongated, conical, composed of more 



1 ' Palaoz. Gebilde Podoliens u. deren Verstein.' Abh. k. k. geol. Eeicbsanst. 

 vol. vii (1874) p. 31. 



2 ' Beiuerk. liber die Podolisch-Galizische Silnrformation u. deren Petref.' 

 Verb. russ. k. mineral. Qesellsch. ser. 2, vol. x (1876) p. 16. 



3 ' Beitrag zur Geol. der Insel Gotland,' Arehiv Naturk. Liv-, Ebst- u. 

 Kurlands, ser. 1, aoI. ii (1861) p. 441. 



