446 ME. S. S. BUCKMAN ON THE BAJOCTAN [Aug. 1895, 



for his Terehratula curvifrons, did not agree at all with those of the 

 fossil called hy that name in France and England. My argument 

 was that this shell ought not to be called ' curvifrons ' ; but that, if 

 the name were applied at all, it should be given to the shell with 

 which the description and horizon agreed. Dr. Davidson, however, 

 was loth to change the use of the name curvifrons, and preferred 

 that the other shell should receive a new name. It was accordingly 

 figured as Waldheimia Haasi, S. Buckm. — Dr. Davidson having 

 asked that MS. names should be given to the shells for convenience 

 of correspondence. 



In restoring Deslongchamps's name of Brebissoni it is not my 

 intention to alter this arrangement. There are, however, two forms 

 known by the name ' curvifrons ' now : — one the fossil which occurs 

 in the Oolite Marl of the Cotteswolds, the other the shell which is 

 found south of the Mendips, and in .Normandy. There are differ- 

 ences between the two forms in the curvature of the valves, in 

 the shape of the beak, and the size of the foramen. It may be 

 that they are geographical races of one species, but it is more 

 probable that they are homceomorphous developments from a common 

 parent. At any rate there seems to be need of distinction between 

 the two forms ; and this distinction may be readily obtained by 

 restoring to the Paris-basin shell the name ' Brebissoni,' which 

 Deslongchamps was laudably ready to drop in favour of Oppel's, 

 and by leaving the name ' curvifrons ' for the Cotteswold fossil. 



That the Cotteswold shell is really Oppel's curvifrons is very 

 doubtful, not only because the description given by that author does 

 not fit the shell, but the horizon is very decidedly different ; and 

 further, the Cotteswold shell had been figured by Davidson as 

 ' Terehratula carinata, var.' Had Oppel wished to name this shell 

 curvifrons, he would doubtless have given a reference to the figures 

 in Davidson's work, 1 a practice which he pursued in other cases. 

 However, this shell has been known as curvifrons for some time, 

 and it may continue to enjoy that name ; but the Paris-basin fossil 

 which was originally called ' Brebissoni ' certainly ought to carry 

 that appellation. There can be no doubt that the latter has a right 

 to this name, but there can be very much doubt as to whether this or 

 the Cotteswold shell have any right to be curvifrons. As they are 

 two distinct forms, the present seems a desirable solution of the 

 question. 



Glossothtris ctjeviprons (Oppel), Davidson. 



1851. Terehratula carinata, Davidson, ' Jur. Brach.' pi. iv. figs. 15, 16. 

 1854j. Terehratula carinata, Davidson, ibid. App. pi. A. fig. 17. 

 1878. Terehratula curvifrons, Davidson, ibid. Suppl. pi. xxiv. fig. 33. 



A dorsally sulcate, ventrally carinate Terebratuloid, the foramen 

 somewhat large, the beak not much incurved. The sulcus longer, 

 wider, and deeper than in Brebissoni. 



Concerning the present restricted application of this name to the 



1 Davidson, ' Jurassic Brachiopoda/ pi. iv. figs. 15, 16, App. pi. A. fig. 17. 



