570 MISS JANE DONALD ON THE GENERA [NoY. I906, 



They resemble, however, some of the other species associated with 

 it by Dr. Ulrich, more especially M. Laphami, Hall, which have 

 more or less flattened instead of concavo-convex whorls and the band 

 situated low down, features which Dr. Ulrich states in his remarks 

 are characteristic of the genus. When a better specimen of Turritoma 

 acrea is figured, should these shells with uniformly-flattened whorls 

 be found not to agree with it essentially, they must constitute 

 a new genus. Hormotoma cingulata, His., as already mentioned, 1 

 and perhaps B. clubia, Don., should be referred here, and also a 

 new and closely -allied species which I am about to describe as 

 Turritoma (?) tenuifilosa. 



This group bears a great resemblance to, and probably may 

 contain, the progenitors of the Devonian Coelidium, Clarke & 

 Ruedemann 2 [Coelocaulus, OEhlert], but it differs from the type of 

 the genus, 0. Davidsoni, (Ehl., 3 in having the sinus in the outer lip 

 deeper, the obliquity of the lines of growth much greater, the base 

 of the shell more flattened, and the outer lip not appearing reflected 

 as in M. (Ehlert's figure. 



As the validity of a species depends in a great measure on the 

 number of forms by which it is represented, I may here state that 

 Mrs. Gray has ten specimens of T. (?) pinguis from the Upper Bala 

 of Thraive Glen, in addition to those already mentioned. There is 

 also an example in the Geological-Survey Collection, Edinburgh, 

 from the same horizon at Drummuck Burn. 



Turkitoma (?) tenuieilosa, sp. nov. (PI. XLIV, figs. 13 & 13 a.) 



Diagnosis. — Shell somewhat elongated, conical, composed of 

 more than seven whorls. Whorls flattened, but slightly convex, 

 broad, ornamented by numerous fine spiral threads. Sinual band 

 situated considerably below the middle of the upper whorls, slightly 

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

 curving very obliquely back to the band above, indistinctly below, 

 and invisible on the band itself. Aperture subovoid. Base appa- 

 rently rather flattened. Test very thin. 



Remarks and Resemblances. — There is but one example 

 of this species in Mrs. Gray's collection, and it is crushed and 

 embedded in the matrix. The body-whorl appears more angular 

 than it must originally have been, owing to its being flattened by 

 pressure ; the outline of the other whorls is also probably rendered 

 less convex by the same cause. It greatly resembles T. (?) polita, 

 Don., but the base is more angular, the band is situated slightly 

 higher on the whorls, and the surface is ornamented by fine spiral 

 lines. It is also like Hormotoma cingulata, His., in the flatness of 

 the whorls, thinness of the test, and in being ornamented by fine 

 spiral lines, but is distinguished by its less elongated form. 



1 Quart, Journ. Geol. Soc. vol. lv (1899) p. 265. 



2 N. Y. State Mus. Mem. 5, ' Guelph Fauna in the State of New York 

 1903, pp. 65-67. 



3 ' Description de qq. Esp. devoniennes de la Mayenne ' Bull. Soc. Etudes 

 Sci. Angers (1887) p. 21 & pi. vii, figs. 4-4 d. (4 e on the plate would seem to 

 ba a misprint for 4 c.) 



