162 R. Etheridge, jun. — Notes on the Gilbertson Collection. 



7. Avicula radiata, Phillips sp. (p. 211, t. 6, f. 8). 



The figure of this species in no way does the specimen justice. The numher of 

 radiating rihs, which are numerous, are not distinctly shown, neither is the full 

 extent of the shell. The posterior wing appears characteristic. By Morris it is 

 placed in Aviculopecten ^ 



8. Gervillia squamosa, Phillips sp. (p. 212, t. 6, f. 9). 



The broad squamose ridges render this species a particularly well-marked form. 

 The vacant space within outline on the left of the figure should represent the 

 internal cast from which the shell has been removed. The lower vacuity is matrix 

 covering up the ventral portions of the valve. It is the Avicula squamosa of Morris. 2 



9. Gervillia laminosa, Phillips sp. (p. 212, t. 6, f. 10 and 11). 



Here, again, the figure does not fully represent the original. The shell is in form 

 quite a Pteronites, only the umbonal slope is too pronounced. There is not that great 

 declivity between the body of the shell and the posterior and anterior wings shown 

 in the figure. Prof. Morris refers the species to Avicula. 3 



10. Gervillia lunulata, Phillips sp, (p. 211, t. 6, f. 12). 



The type is a beautifully preserved shell in limestone. Prof. Phillips's figure has 

 been a little restored about the beaks and posterior margin. There is another large 

 example, without any trace of shell remaining, measuring as much as four inches and 

 a half in its longest diameter by two and a half. And yet another specimen nearly 

 as large. The species is placed in Avicula by Prof. Morris.* 



11. Gervillia inconspicua, Phillips sp. (p. 212, t. 6, f. 13). 

 Not in the Gilbertson Collection. 



12. Perna? Phillips sp. (t. 6, f. 14). 



This is the internal cast of a Myaliniform shell in limestone, without any 

 characters whatever by which it can be identified. 



13. Pecten ellipticus, Phillips sp. (p. 212, t. 6, f. 15). 



The hinge characters are exceedingly well shown in this cast, although not 

 illustrated in the figure. It is an Entolium, and not very far removed from E. 

 Sowerbii, M'Coy. It is the Aviculopecten ellipticus of Morris. 1 



14. Pecten hemisphericus, Phillips sp. (p. 212, t. 6, f. 16). 



The shell which is marked in the Collection as the type of this species has either 

 been injured since the figure was drawn, or the latter was somewhat restored. It is 

 deficient around the ventral margin. 



15. Pecten dissimilis, Phillips sp. (p. 212, t. 6, f. 17 and 19). 

 I am only able to satisfactorily recognize the specimen from which fig. 17 has 



been taken, and I must for the present refrain from expressing any opinion on the 

 identity, or otherwise, of Aviculopecten dissimilis, Fleming, and A. dissimilis, Phill. 

 The subject of fig. 17 has remarkably close and concentric lines covering the whole 

 surface of the valve. 



16. Pecten stellaris, Phillips sp. (p. 212, t. 6, f. 18). 

 The ribs in the type are of a much less prominent nature than shown in Phillips's 



figure, and there are three distant concentric lamellae. This and the Avicula tessellata 

 are very much alike in the nature of the ribbing, only in P. stellaris the ribs are 

 much more numerous, the anterior ear is divided off from the body of the shell, and 

 there is no obliquity, as in Avicula tessellata. 



17. Pecten arenosus, Phillips sp. (p. 212, t. 6, f. 20). 

 There is no shell at all resembling this figure in the Gilbertson Collection. From 



the appearance of the figure I should imagine it represents an imperfect shell. 



18. Pecten plicatus, J. de C. Sowerby (Phillips, p. 212, t. 6, f. 21). 

 I have compared this with Sowerby's type and find that it corresponds in every 



particular, except that in the type the ribs are finer and more numerous. In the 

 Phillipsian shell the posterior wing is deficient, it really runs out to an extended 



1 Cat. Brit. Foss. 2nd ed. p. 165. 2 Ibid, p. 162. 3 Ibid, p. 162. 



1 Ibid,^. 162. 5 Catalogue, 2nd ed. 1854, p. 164. 



