Observations on some of the Loxonematidæ, with Descriptions of Two New Species

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Abstract
T he genus Loxonema was founded by Phillips in 1841, and was thus described by him:— ‘Spiral, turriculated; whorls convex, their upper edges adpressed against the next above; without spiral band; mouth oblong, attenuated above, effused below, with a sigmoidal edge to the right lip; no umbilicus (?); surface covered by longitudinal threads or ridges, generally arched.’ He further states that these observations are merely provisional, until the form of the aperture is more perfectly known. In noting the number of species, he writes that most of them are probably ‘varieties of three or four types having L. sinuosa for one extremity and L. Hennahii for the other; a second related to L. tumida and L. lincta ; a third to L. rugifera .‘ [ Loc. cit. ] Later researches show that this description is correct for the group of shells having Loxonema sinuosum for the type, and the generic name must be restricted to them. The essential characteristics are the possession of whorls adpressed at the suture and the presence of strongly-sigmoidal lines of growth. Shells having more convex whorls, or less sigmoidal lines of growth, must be placed elsewhere. Prof. Koken and other palæontologists have created several new genera for some of these latter. The type, Loxonema sinuosum , is the first species described by Phillips: it is a Devonian form from South Petherwyn, which he identifies with Terebra (?) sinuosa , Sow. from the Aymestry Limestone. They are probably distinct species, although Mr. Whidborne thinks them correctly identified. The striæ on the Devonian form

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