Raymond: Gastropoda of the Chazy Formation. 171 



Class GASTROPODA. 



Order ASPIDOBRANCHIA Schweigger. 



Sub-Order DOCOGLOSSA Troschel. 



Family Patellid/E Carpenter. 



Genus Archinacella Ulrich and Scofield. 



Archinacella deformata (Hall). 



(Plate XLVI, figures i-6. ) 



Orbicula ? deformata Hall, 1847, Paleontology of New York, Vol. 

 I, p. 23, PL 4, figs. \oa, 10b. {Orbicula deformis, in explanation 

 of plate.) 

 Metoptoma ? dubia Hall, 1847, ibidem, figs. 11 a, 11b. 

 Metopioma deformis Billings, 1863, Geology Canada, p. 937. 

 Stenotheca dubia Whitfield and Hovey, 1898, Bulletin American Mu- 

 seum Natural History, Vol. XI, p. 58. 

 Archinacella ? deformata Raymond, 1905, American Journal of Sci- 

 ence, Series 4, Vol. XX, p. 875. 



An examination of the types shows that Whitfield and Hovey were 

 correct in referring the specimen named Orbicula ? deformata by Hall 

 to the species Metopto?na ? dubia, which Hall described on the same 

 page of Vol. I, New York State Paleontology. The species should, 

 however, take the first specific name applied to it. 



It is evident that Billings saw the true nature of Orbicula ? defor- 

 mata, for as early as 1863 he referred it to the genus Metoptoma. 

 (See the paper cited above. ) 



As no specimens have been found which show either muscle scars 

 or pronounced surface markings, the generic reference is somewhat 

 uncertain. It does not seem possible either to leave it in the genus 

 Metoptoma, where Hall doubtfully put it, or in the genus Stenotheca, 

 where it was placed by Whitfield and Hovey. In general form it 

 most resembles the shells of some of the species of Archinacella de- 

 scribed by Ulrich and Scofield, and until better specimens are obtained 

 it may be placed in that genus. The specimens of this shell are abun- 

 dant, and the characters are quite constant. It is easily recognized by 

 the low form and by the anterior position of the apex. 



