APPENDIX. 323 



Avlysia? asciola, S. Wood. Tab. XXXI, fig. 24 a, b. 



Locality. Cor. Crag, Sutton, Sudbourne. 



This fossil has been in my possession for the last twenty years, with the above doubtful generic name, 

 and my endeavours to obtain information as to its true character have hitherto been unsuccessful. There is 

 a strong resemblance between it and one of the opercular valves of a Barnacle (tergum), but, with all my 

 search, I have never been able to find what might be considered as its opposing portion — all my specimens 

 have the point or apex inclining in the same direction ; still I thought it might possibly belong to the 

 Cirripedia ; I therefore requested Mr. Darwin would be kind enough to give me his opinion upon them, 

 but they were rejected by him as not belonging to any animal in the group he has so ably 

 investigated. 



Its form is that of a " little hatchet," and I have assumed it to be the calcareous portion of an internal 

 shell, belonging, probably, to the section called Aclesia by Rang, and have placed it provisionally in the 

 above generic position. At least fifty specimens have been found by myself, and these present considerable 

 variation inter se, but I think they may be all referred to the same specific animal. One specimen is from 

 Sudbourne ; and this, though more than double the size of those from Sutton, was probably only from a 

 larger individual, varying in that respect like the specimens of Scalpellum, as well as a few of the Mollusca 

 from the same two localities. 



Two fossils from the Upper Tertiaries of Sicily have been doubtingly described as species under the 

 above generic title. 



The inner portion or lining of Pectunculus glycimeris sometimes separates from the rest of the shell, 

 and is occasionally found in the Red Crag ; and when in that condition it strongly resembles the figure of 

 Aplysia grandis, Philippi, 'En. Moll. Sic.,' vol. ii, t. 18, fig. 10, a, b ; but I have not been able to see the 

 Sicilian fossil. 



Pecten maximus. Tab. XXXI, fig. 25. 



Pecten maximus. S. Wood. Monog. of Crag Moll., ante, p. 22. 



A single specimen of the flat valve of a species in this genus has lately been given to me by Mr. 

 Whincopp, who obtained it from Sutton. 



Although a considerable amount of variation is exhibited in my large series of specimens of what I have 

 considered as P. maximus from the Coralline Crag, I have not seen anything quite so anomalous as is 

 presented by this Red Crag specimen, and confess to be somewhat perplexed respecting it ; still there is 

 something peculiar in the arrangement of the ribs of this shell to warrant the belief that there has been a 

 failure in their number of about one half, perhaps caused by what might be called a duplicature or union of 

 the organs by which they were produced, and that it is nothing more than a monstrous form of the common 

 British species. 



There are six, or perhaps eight ribs, including those irregular ridges at the shoulders, rounded and 

 smooth, probably made so by attrition ; between them are some smaller rays, varying from two to five. In 

 the recent shell these intermediate rays are also variable, and, in some specimens, they are very distinct and 

 prominent, both between and upon the ribs, while in others they are entirely absent. 



In order, therefore, to avoid the introduction of a species upon the slender evidence afforded by this 

 specimen, I have called it P. maximus, var. larvatus. 



