88 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. ' [DeC. 6, 



anterior, acute. Surface concentrically marked by numerous lines of 

 growth. Anterior side well rounded ; posterior subacute. Length 

 ■| to IL inch ; breadth |^ths of length. 



Locality and 'position. — Sutton quarries, Sutton series. 



The form of this shell renders it probable that it is a Cyprina. I 

 have not seen the hinge, owing to the unfavourable state of the 

 matrix. 



25. Anatina precursor, Quenst., var. Pylensis. PI. lY. fig. 5. 



Shell flatly convex, transverse, inequilateral. Anterior end 

 rounded ; posterior end slightly produced, narrower, 5iid somewhat 

 depressed. Lines of growth consisting of from six to ten concentric 

 rounded folds, which extend along the shell, being nearly as distinct 

 posteriorly as anteriorly. A slight ridge proceeds from the umbo to 

 the postero-ventral margin. Ventral margin rounded. Umbones sub- 

 central, depressed posteriorly. Length 1^ inch ; breadth half of 

 length. 



Locality and position. — Avicula-contorta sandstones at Pyle, Stormy 

 Down, &c. 



This shell differs from the description given by Oppel and Suess in 

 being considerably shorter posteriorly. It approaches thus more to 

 the form of A. Buessii, but it lacks the median depression which hol- 

 lows out the ventral margin of that species. It differs from Oppel's 

 figure of A. prcecursor by the extension of the folds along the posterior 

 part of the shell as they curve round to meet the dorsal margin. 



These difi'erences are perhaps enough to constitute a new variety, 

 but do not, I believe, necessitate the formation of a new species. 



26. Patella Stjttonensis, spec. nov. PI. lY. figs. 9 a, 9 6. 



Shell convex, oval. Apex not quite central, but nearest the pos- 

 terior margin, and the highest point of the shell. Surface covered 

 with regular, elevated, slightly imbricated, concentric lines, which 

 become a little fainter near the apex. Length | inch ; breadth |ths 

 of length. 



Locality and position. — Sutton quarries, Sutton series. 



This shell has much the aspect of a Discina ; but as it is not horny 

 in texture (neither have I found a lower valve), I refer it to this 

 genus. 



It resembles Patella elUptica, from the Muschelkalk, and also 

 P. Hettangiensis, from the Angulatus-beds of Hettange ; it clearly 

 differs, however, from these species. The form differs from P. Het- 

 tangiensis in the region of the apex especially. 



27. Chemnitzia, sp. 



There is a large univalve shell, 4| inches long, common in a bed 

 near the middle of the Southerndown series ; natural sections of the 

 shell, showing the columella, may sometimes be seen on the beds, 

 which have been slightly polished by the sea. I have no specimens, 

 owing to the difficulty of breaking up the beds at this place. 



