On Dracliiopod ]Somenclature. 223 



XXXVI. — Brachtopod Nomenclature : Seminula, &g. 

 Bj S. S. BUCKMAN, F.G.S. 



In this Magazine (vol. xviii. 1906, p. 324) I put forward 

 certain views regarding the genus Seminula. In the same 

 Magazine (vol. xix. 1907, p. 194) Dr. Vaughan contested 

 my conclusions. I liave also been favoured with certain 

 verbal criticisms concerning them. 



The gist of the verbal criticisms may be given first. They 

 are to this effect — that Terehratula pentaedra, Phillips, ought 

 not to be taken as the type of Seminula: that M'Coy, in 

 using a trivial name as a generic term, indicated exactly the 

 type of his genus : that, therefore, T. semimda is the type of 

 Seminula : that M'Coy himself subsequently confirmed this, 

 as Dr. Vaughan points out. To which I may add that, if 

 the type was considered doubtful before, then M'Ooy becomes 

 the first one to select a type to his genus; and that therefore 

 subsequent authors are barred from selecting outside his 

 limits. 



The difficulty in this case is that M'Coy himself, when 

 he made tliis selection, confused as Seminula seminula speci- 

 mens of Dielasma ; but we have it on Davidson's authority 

 (Carb. Mon. p. 16) that the original of Seminula pisuin, as 

 M'Coy called Phillips's Terebratida seminula, is a Rhyncho- 

 nella [Camarophoria], As that is what M'Coy originally 

 had in his hand in naming his species and genus, then if the 

 views prevail that M'Coy's selection of a trivial name for 

 a generic is a better indication of his type than his giving 

 a figure, the type of Seminula, M'Coy, will be T. pisum = 

 Ter. seminula. The result will be the same as in ray previous 

 paper — that Seminula is a genus akin to Camarophoria. 



Now as to Dr. Vaughun's observations on Ter. pentaedra. 

 He says that the type of this species is in the British 

 Museum ; but I had come to the conclusion that this was 

 not the type. This alleged type Dr. Vaughan says is con- 

 specific with S. amhiguus : I find so many differences that I 

 cannot regard it as congeneric. The most important point 

 is the contour of the beak-region. In S. amhiguus the dorsal 

 umbo is not prominent, and on each side of it the two valves 

 join flush : it has a thorough Terebratuloid contour. In 

 the " T. pientaedra " the beak-region has what may be called 

 a spiriferoid contour : the umbo is very prominent and the 

 two valves join to make a flange each side of it, features 

 which are seen in Spiriferids. These same features I find 

 in the specimens accompanying the alleged T. pentaedra : 



