32 



Length, forty-five millimetres: breadth, thirty-eight mm. : maximum 

 height, seventeen mm. : height of lower surface of apex from the base, 

 seven mm. 



Hespeler: T. C. Weston, 186Y : a single but perfect cast of the 

 interior of the shell. 



SOENELLA CONICA. (N. Sp.) 

 Plate 5, figs. 2 and 2a. 



Shell small, conical, moderately elevated, the height being equal to 

 one-half the length of the aperture or base : sides slightly compressed : 

 apex pointed, erect and almost central, but placed a little nearest to the 

 narrowest end : base or aperture ovate or subovate in outline, about 

 one-fifth longer than broad ; surface markings and muscular impres- 

 sions unknown. 



Length of an average specimen, ten millimetres : breadth of the 

 same, eight mm. : height, five mm. 



Durham : J. Townsend : eight tolerably perfect but not very well 

 preserved casts of the interior of the shell. 



The genus Scenella of Billings has never been properly defined, and 

 consequently ought either to be re-constituted or abandoned. The 

 " obscure carina extending from the apex down one side to the margin," 

 given as part of the diagnosis of S. reticulata, is not even a constant 

 specific character, for there is no such keel on an exceptionally large 

 specimen of that species from the typical locality in the Museum of 

 the Survey. The surface ornamentation, too, upon which the genus 

 was mainly based, is clearly of not more than specific importance. 



The specimens from Durham described above are here placed pro- 

 visionally in the genus Scenella on account of their very close resem- 

 blance in external form to S. reticulata, but the muscular impressions, 

 which would probably afford the sm-est indications of the true afl3.nities 

 of both, are entirely unknown. They may, however, be referable to 

 Whitfield's genus Lepetopsis. 



In the second volume of the "Palaeozoic Fossils'' of Canada, on page YY, 

 Stenotheca pauper and Scenella reticulata are described under the head 

 of Hurmian fossils, whereas both of these species are from the Menevian 

 limestones of Conception Bay, Newfoundland, which directly overlie 

 the black shales or slates of the "Acadian " Group or Lower Cambrian 

 of that Island. 



