Fossil Fauna, Tabic Cape Beds, Tasmania. 91 



25. Lyria semiacuticostata, sp. nov. Plate II., fig. 8. 



Shell somewhat thin, o\-ate-fusiform, with a well-elevated acute 

 spire, and with the anterior truncated at the end of the short 

 broad canal. 



Apical angle al)out fifty degrees. Spire consisting of a very 

 small obtuse embryo of two-and-a-half smooth, gradually increas- 

 ing, slightly convex whorls, the apex of which is central, suc- 

 ceeded by six or seven much more rapidly increasing, slightly 

 convex and costated whorls, with a rather deeply impressed and 

 well-defined suture. Spire-whorls somewhat shouldered at the 

 suture, owing to the form of the transverse costse, otherwise 

 regularly convex, with their greatest convexity about the middle 

 of each whorl. 



Aperture oval, acute posteriorly, and opening into the short 

 broad canal anteriorly ; outer lip much thickened, smooth within, 

 gently sloping from the suture, then more suddenly and obliquely 

 inwards as it joins the anterior end of the canal ; inner lip with 

 an enamel coating which is thickest at the extremities, almost 

 thinning out medially. Columella with three strong oblique 

 plaits at the anterior end, the medial one being the strongest ; 

 these are succeeded by about twelve ridges, gradually diminishing 

 towards the posterior end, the latter being furnished with a 

 strong tooth-like projection a little below the junction of the 

 outer lip with the body-whorl. Canal slightly bent to the right, 

 then recurved. 



Surface ornamented with slender, acute, very slightly oblique, 

 transverse cost*, which are most i-egularly and strongly developed 

 on the earlier or posterior spire-whorls, and tend to become 

 obsolete on the body-whorl, though still visible in some specimens 

 as short angular elevations in the neighbourhood of the suture. 

 The costre have a more gradual lateral slope on their left side 

 than on their right, where they are much more abrupt, this 

 feature being most noticeable at the posterior suture of each 

 whorl, as it gives rise to the sharp angular terminations at this 

 extremity. Towards their opposite extremity they tend to fade 

 away entirely, as may be noticed on the penultimate and more so 

 upon the body-whorl. In number the costie are slightly variable, 

 some specimens being more closely costate than others. In all 



