198 RECOEDS OF THE ATJSTRALIAN MUSEUM. 



A glance at this table will indicate that the concealed sutural 

 position of the band on the earlier whorls at once separates 

 Keeneia from the other "sub-genera " named. 



At first sight, ill-preserved examples of K. platyschismoides 

 may be mistaken for Platyschisma oculus. In the latter, how- 

 ever, there is no band on the obtuse peripheral angle of the 

 body-whorl. To be certain on this point, a very large number 

 of P. oculus were carefully examined by Messrs. C. Hedley and 

 W. S. Dun, irrespective of myself, and in no single instance 

 did any shell that could satisfactorily be referred to P. oculus, 

 present even the semblance of a band, but only a slight inflection, 

 or curving backwards of the growth laminpe and stria? on passing 

 over the obtuse periphery, and corresponding to the slight insinua- 

 tion in the outer lip, when perfect, in accordance with the generic 

 definition of Platyschisma, as given by McCoy. " 



In Keeneia platyscJtisrnoides, on the other hand, there is aflattened 

 band along the obtuse periphery of the body-whorl, defined by 

 faint impressed encircling lines. The transverse sculpture, in- 

 stead of passing over simply with a roll, as in P. ocuhis, is, on 

 arriving at this band, deflected backwards; and on the opposite 

 side of the band or base of the shell, directed forwards to pursue 

 its regular course. On the band the strije are deeply concave 

 backwards. As before stated, this band is only visible on the 

 body- whorl, for on arriving at the penultimate whorl it becomes 

 sutural, and concealed by the overlap of the body-whorl. That 

 such is the case is abundantly proved by examples in which the 

 test of the body-whorl has been broken away, when the band is, 

 as a rule, beautifully exposed on the penultin)ate whorl. On the 

 other hand, if specimens of P. oculus in a like state of preservation 

 are examined, no trace of a band whatever is observable. 



As the facts now recorded have been tested through the medium 

 of a number of specimens, it is legitimate to assume that we have 

 here a shell entirely distinct generically and specifically from 

 Platyschisma oculus. 



Genus Keeneia, gen. nov. 



Gen. Char. — Shell turbinate or trochiform, umbilicate. Whorls 

 few, more or less tumid and lounded. Mouth large, oblique; outer 

 lip subacute, insinuated by a rather wide and shallow sinus; inner 

 lip thickened but not reflected, or with a callosity. Band median 

 or submedian on the body-whorl only, sutural and concealed on 

 the others. Umbilicus infundibuliform, without keel. 



Type. — Keeneia platyschismoides. 

 2 McCoy—Synop. Carb. Lime. Foss. Ireland, 1844, p. 38. 



