Vol. 55.] ECIOMARIA AND HORMOTOMA. 255 



the varieties Peachii, orientalis, and occidentalis, are probably merely 

 variations of one common form. Eunema prisca of Billings/ as 

 described by him and also by Ulrich & Scofield, appears to be 

 another but more slender variety of the same type in which bhe 

 uppermost keel is absent. The variety Peachii greatly resembles 

 M. Adelina, Billings,^ in the style of the ornamentation, but that 

 species attains a much greater size and has a smaller spiral angle. 

 The lines of growth are not well preserved, but where seen on the 

 varieties Peachii, orientalis, and the form in the British Museum, 

 they accord with those characteristic of the genus Ectomaria. 



Dimensions. — There are four examples of this variety in the 

 Edinburgh Museum, which are all more or less imperfect and 

 weathered. That figured (PI. XXI, fig. 1) is distorted obliquely, 

 the apex is broken, and only five and a quarter whorls remain, 

 whose length =13 mm,, width =6| mm. A fragment of a larger 

 specimen consists of three whorls, measuring 9;^^ mm. in length, and 

 1\ mm. in width (PI. XXI, fig. 2). 



Locality and Horizon. — Durness Limestone, Sutherland, 

 which is regarded as either Upper Cambrian wholly or in part, or 

 else Lower Ordovician. 



ECTOMAEIA PAGODA (Salt.) Var. ORIENTALIS uov. (PI. XXI, figs. 3 & 4.) 



Description. — Shell very elongated, turreted. Whorls numbering 

 more than nine, increasing gradually, wide. Ornamentation consist- 

 ing of two strong, slightly crenulated keels, the strongest of which 

 is situated near the middle of the whorls of the spire, and slightly 

 above the middle of the body-whorl, the other is a little distance 

 below, and is not quite so prominent ; there is a very fine thread 

 immediately below the suture, and also an additional strong keel on 

 the body- whorl. The spaces between the keels are somewhat con- 

 cave ; the uppermost is the widest, and the lowermost the narrowest. 

 Lines of growth indistinct, apparently sloping backward to and 

 forward from the space between the two strong keels. Sutures deep. 

 Aperture subquadrate, slightly channelled below. 



Remarks and Eesemblances. — This appears to be an even 

 more decided variety of E. jpagoda than the var. Peachii. The form 

 is more slender, the whorls are rather higher, the central keel stronger, 

 the space between it and the keel below wider, and the lowest space 

 narrower. It comes very near the variety called occidentalis by 

 AVhiteaves,^ as he states that his shell has a proportionately broader 

 slit-band, but his specimen is of much greater size than any of the 

 Scottish examples that I have seen, and, as he does not figure the 

 shell, it is impossible to ascertain whether it agrees in other 

 particulars. 



Dimensions. — There are about ten specimens of this form in 

 the Geological Survey Collection, Edinburgh Museum. That figured 

 in PI. XXI, fig. 3, has the apex broken, and only six whorls remain, 



1 Can. Nat. & Geol. vol. iv (1859) p. 360 & fig. 8 1. 



2 Geol. Surv. Can. ' Pal. Foss.' vol. i (1865) p. 231 k fig. 217. 



3 Ihid. vol. iii, pt. in (1897) p. 193. 



