Yol. 55.] ECTOMARIA AND HOEMOTOMA. 257 



E-esemblances. — It most nearly resembles E. priscci, Billings, 

 but is much smaller ; the whorls are higher, and the two strong 

 keels are nearer the middle of the whorl. Erom E. pagoda, the 

 British varieties Peaohii and orientalis, and E. glrvanensis, it is 

 distinguished at once by its much smaller size and by its more slender 

 form. 



Dimensions. — The fragment, consisting of about four whorls, 

 is embedded in the matrix, and measures 6| mm. in length, the 

 width of the penultimate whorl being 2^ mm. 



Locality and Horizon. — In rocks of Llandeilo [Lap worth] 

 age at Minuntion (Aj'rshire). 



Genus Hoemotoma, Salter, emend. 



Sormotoma, J. W. Salter, 1859, Geol. Surv. Can. ' Canad. Organ. Eem.' dec. i, 

 p. 18 (Section 2 of MurcMsonia). 



[The full synonymy is given separately with the descriptions of the different 

 species.] 



Description. — Shell elongated, composed of numerous bead-like, 

 convex or subangular whorls, which are more or less smooth, being 

 devoid of prominent ornamentation. Aperture subovate, narrow 

 and produced below. Outer lip having a deep V-shaped sinus, which 

 gives rise to a band on all the whorls. This band is flat or slightly 

 concave, rarely somewhat raised, being generally more or less level 

 with the surface of the whorl, and is margined by a slight thread on 

 each side, or else it is merely defined by the lines of growth, its 

 limitation being frequently indistinct. The lines of growth curve 

 very obliquely back to the band above, and still more strongly for- 

 ward below. Inner lip reflected on the body- whorl, and sometimes 

 covering a minute umbilicus. 



Dimensions. — The length varies from about 20 up to 200 mm. 



Remarks. — This group of shells was separated from the typical 

 Murchisonice by Salter, on account of its having convex bead-like 

 whorls, and he gives M. gracilis, Hall, from Pauquettes Rapids, as 

 the type. Ulrich & Scofield ^ have since shown that Salter's shell 

 is distinct from that of Hall, and they designate it H. Salteri. Salter 

 states that the aperture is rounded, instead of being produced and 

 effuse below as in Murchisonia ; but this is not really the case as 

 may be seen by referring to Ulrich & Scofield's description and 

 figures ^ (op. cit. p. 1016 & pi. Ixx, figs. 44-51) or to some specimens 

 (G. 11490) from Allumette Island, in the British Museum (Nat. 

 Hist.), which in other respects agree with the description and figure 

 of II. Salteri (gracilis) as given by Salter. His specimen was 

 evidently imperfect, and does not show the prolongation of the aper- 

 ture, though the reflection of the inner lip is preserved. The most 

 distinctive features of Hormotoma, besides the bead-like whorls, are 

 the very oblique direction of the lines of growth, which indicate that 



1 Final Rep. G-eol. & Nat. Hist. Sary. Minn. vol. iii, pt. ii (1897) p. 1016. 



■■^ The figures of some of the varieties of H. gracilis, Hall, as represented by 

 Ulrich & Scofield {op. cit. pi. Ixx, figs. 20, 26, 31 & 36) show the characteristic 

 elongation of the aperture better than the figures of H. Salteri. 



a.J.G.S. No. 218. s 



