240 Reports and Proceedings— Geological Society of London. 



This paper deals with the tliphyoid Terebratulee, of which so 

 many species have borne the name Terehratnla diphya (Colonna). 

 It is pointed out that this name is pre-Linnean, and can onl^' dat& 

 from the time when it was revived by L. von Buch in 1834. Prior 

 to that several names had been given to these shells. The first were 

 Terehratnla cor and T. pilens given by Bruguiere in 1792 in the 

 Journal cVBistoire Naturelle, his paper in which has been entirely 

 overlooked by workers on these shells. Brugiiiere's names indicate 

 a perforate and an imperforate species respectively. Consideration 

 is tlien given to the synonymy of certain diphyoid species: — 

 T. triangnJus, Valenciennes, in Lamarck, which was actually founded 

 on Bruguiere's own figures of his T. pileiis; T. triqnetra, Parkinson, 

 which includes two species, a perforate and an imperfoi'ate ; and 

 T. antinomia, Catullo, which covers various species. These and 

 others all antedate T. diphya, L. von Buch. 



It is pointed out that Terehratnla diphya is not the type of 

 the genus Pygope, as all text-books say ; for Link, the autlior of th& 

 generic name, referred only to T. antinomia, Catullo. Reasons are 

 given for taking as the type of Pygope one of the forms of T. antinomia 

 which is considered to be the same species as T. deltoidea, Val. 

 Then the latter generic name Antinomia, Catullo, is discussed. The 

 genus was founded on five species, and one of them is now selected 

 as the type — the genolectotype. This is A. dilatata, Catullo, supposed 

 to be equivalent to Terebratida antinomia, Catullo, that is, to what is 

 now selected to be the type of that species. In that case the species 

 "would bear the name Antinomia antinomia (Cat.). The two generic 

 names Pygope and Antinomia are employed, because they are supposed 

 to indicate two independent parallel genetic series, whose members 

 difi'er in size and position of the perforation, and in characters of the 

 lateral margin. But there is yet another series of diphyoids, typified 

 by Terebratida diphyoides, d'Orb. It is pointed out that, although 

 the species covered by the name diphyoides are very like Pygope a& 

 now used, yet they all differ in having particular characters in the 

 preperforate stage — a dorsal ridge and a ventral sulcus. For thi& 

 series de Haan's MS. name Pygites is used ; and it is supposed that 

 there are three genetic series of diphyoids which have developed 

 independently, and that the remarkable perforate form, with its two 

 lobes joined, has been evolved three times over. A genetic plate is 

 given, figuring for comparison many of the species in the three 

 series, showing their development from the glossothyridoid, to the 

 bifidate, to the perforate (ordinary T. diphya) stage ; and that then 

 they finish by losing all trace of the perforation, the lobes completely 

 coalescing (the imperforate stage), represented by Terebratida pileus, 

 Brug.rrT. triangidus, Val. in Lamarck. 



Synonymies and short notices of the species in the three genera 

 have been given. In compiling them there have been found two 

 papers overlooked by Brachiopod bibliographers — one by E. Newman 

 in the Zoologist, naming T. Ditvali, and one by Catullo. 



