ALARIA. 141 



unknown) ; these are very angular, with the keel slightly above the middle ; ante- 

 rior portion of each whorl marked by straight regular longitudinal costae, close set, 

 not less than a dozen in number, with a marked slope from right to left. The 

 spiral lines are fine and numerous in the posterior areas, which are entirely devoid 

 of longitudinal ornament, the spirals in the anterior areas are coarser and wider 

 apart, decussating visibly with the longitudinals. Spiral lines may also be detected 

 on the body-whorl, but no costge. There is one prominent median keel, armed with 

 a short spur, rather more than a quarter of a turn above the base of the wing, 

 which is short. The nature of the digitation, if any, is unknown. 



Aperture apparently trapezoidal, the outer lip enveloping the anterior half of the 

 penult. Other indications wanting. 



Relations and Distribution. — The character of the spire is not unlike that of Al. 

 hamus, the turriting being distinctly mural. It somewhat resembles a figure given 

 by Piette (op. cit., p. 44, pi. v, fig. 6) of a variety of Al. hamus from the Fuller's 

 Earth of Les Clappes, which that author considered might be a distinct species ; 

 but his description does not tally quite so well, since he indicates only eight or 

 nine costse on the whorls of the spire. Only one specimen of Al. hamoides has yet 

 been found with the body-whorl preserved, and the indications are not altogether 

 reliable. At present it is only known to occur in the Lincolnshire Limestone at 

 Great Ponton, where portions of the spire have been found from time to time. 



61. Alaria (? Diartema 1 ) varicipera, sp. nov. Plate II, figs. 10 a, 10 b ; Plate VII, 



figs. 8 a, 8b; figs. 8' a, 8' b. 



Description. — The specimens found in the Lincolnshire Limestone at Great 

 Ponton (fig. 8 a, and fig. 8 b) differ to a certain extent from those occurring at 

 Weldon (figs. 8' a, 8' b), and these again present some differences between them- 

 selves. Amongst the specimens figured we recognise three different forms, which 

 have certain features in common, but which differ in the final development. These 

 forms may represent varieties or different stages of the same species. Describing 

 the common features — 



The shell is turrited and fusiform, apical portion of the spire blunt, with a 

 convex angle and smooth whorls. The whorls of the remainder of the spire are 

 angular and carinated, the carina being nearly median. The longitudinal orna- 



1 Piette, 1864. The forms now under consideration differ so widely from Alaria that they are 

 only placed under that genus provisionally. They do not correspond exactly with Diartema. Beyond 

 the obvious fact that they belong to the Aporrhiiidse it is not very clear to what genus we should 

 refer them. 



