306 MES, JAXE LOXGSTiFF 0>' SOME ^-E"V^" [Sept. I912, 



TxEio>-EirA. gen. uov. 



Diagnosis. — Shell conical, of moderate height, composed of 

 convex whorls ornamented by numerous strong, raised, sigmoidal 

 and slightly oblique threads. Above the middle of each whorl is a 

 narrow groove cutting across the oblique threads : the portion of 

 these above is concave forwards, and ends somewhat abruptly at the 

 groove : that below is at first for a very short length greatly curved 

 forwards, and tlien passes downwards with less obliquity. So lines 

 of growth are observable in the groove, and it is devoid of bordering 

 lines. Base slightly produced. Columella straight. Inner lip 

 reflected. Aperture subovoid. !N"o umbilicus. 



Genotype. — Tnutonema subsulcatwu, sp. nov. 



Remarks and resemblances, — The only species known to 

 me is represented by two specimens which are remarkably well 

 preserved. The genus is like JlacrocTiilina Bayle in shape, 

 Lo:conema Phill. in having strong oblique threads, and Aclisina De 

 Kon. in the curve of the latter. It differs from all three in possessing 

 a very fine spiral groove on all the whorls, and is further dis- 

 tinguished from Jlacrochilina by the form of the aperture, from 

 Loxonema in the whorls not being adpressed at the suture, and from 

 Aclisina in being less slender and without spiral threads. The 

 narrow groove, which is suggestive of a slit in the outer lip, causes 

 it to resemble MurcMsonia D'Arch. & De Vern. It is not clear, 

 however, whether this groove really represents a slit or whether 

 it is merely a deep narrow depression in the test, as neither specimen 

 has the outer lip entire. It differs from ILurcliisonia in the lines 

 of growth above not curving backwards, and in the groove being 

 devoid of bordering threads or lines of growth. The commencement 

 of the ornamentation cannot be ascertained, as the earlier whorls 

 are worn smooth. The protoconch appears to be simply coiled on 

 the same plane as the rest of the spire, but it is impossible to define 

 on account of imperfect preservation. 



It is difficult to know where to place this genus, and for the 

 present it is perhaps best to refer it to the family ^lurchisoniidce. 



Tmeio>'ema srBsuLCATrAi. sp. nov. (PI. XXVIII, figs. 3 a-4 5.) 



Diagnosis. — Shell very small, composed of about seven whorls. 

 As only one species is known, there is little to add to the generic 

 description. 



Dimensions. — There are but two specimens in the collection 

 of Mr. John Smith. Dykes (Ayrshire). The larger example con- 

 sisting of seven whorls, measures 2-5 millimetres in length aud 

 1-5 mm. in width. The other has six whorls in a length of 2-25 

 mm. : its greatest width=l-25 ram. This latter must be regarded 

 as the holotype, as it shows the aperture as well as the apex. 



Locality. — High Smithston, Kilwinning (Ayrshire). 



Horizon, — Upper Limestone Series (of Scotland). 



