36 Mr. W. King on certain Genera 



the former as in the latter. They do not appear to have been 

 noticed in any tertiary and recent Terebratulas : they are to be 

 seen in Terebratula digona, T. obovata and T. oblonga, but are ab- 

 sent in many others agreeing with them in geological age, from 

 which I am led to believe that they are only partially present in 

 the secondary Terebratulas : they appear however to be general 

 to the palaeozoic species. With some exceptions, as in certain cre- 

 taceous and other species, the condyle plates are to be found in 

 all the Hypothyrises living and extinct. 



In addition to those given in the synoptical table, the family 

 Terebratulidce has been made to include other genera, as Trigono- 

 semus, Konig, Rynchora, Dalman, Magas, Sowerby, Pygope, Link, 

 Delthy7idaa, M'Coy, Semiluna, &c. As I am not sufficiently ac- 

 quainted with secondary species to pass an opinion on these 

 groups, I will leave to others better qualified than myself the 

 task of analysing them. The genus Semiluna, M'Coy, I am 

 strongly disposed to think is founded on young Hypothyrises. 



Strophomena and Lept^ena. 



It is now a generally received rule that " the name originally 

 given by the founder of a group or the describer of a species 

 should be permanently retained to the exclusion of all subsequent 

 synonyms*." This is especially applicable to a group of Pallio- 

 branchs next to be considered. 



Many years ago Rafinesque proposed the genus Strophomena : 

 I do not know the exact time of its publication, but for a cer- 

 tainty it was previously to 1825, as Blainville adopted it in his 

 ' Manuel de Malacologie/ published in that year. The genus is 

 thus described by Blainville : — " Coquille equilaterale, reguliere, 

 subequivalve ; ayant une valve plate et P autre un peu excavee ; 

 articulation droite, transverse, offrant k droite et a gauche d'une 

 subechancrure mediane, un bourrelet peu considerable, crenele 

 ou dente transversalement ; aucun in dice de support." The il- 

 lustrative species (Strophomena rugosa, Raf.) figured in the ' Ma- 

 lacologie ' is evidently closely allied to and congeneric with Lep- 

 tcena alternata. 



Subsequently to Rafinesque, Dalman (in 1827) proposed a 

 new genus under the name of Leptana, in which he included the 

 so-called Leptcena rugosa, L. depressa, L. transversalis and L. eu- 

 glypha, which have generally been considered to belong to the 

 same genus as Strophomena rugosa. It is thus evident that the 

 name Strophomena has the priority over that of Leptcena, which 

 is the reason, it may be presumed, why so many continental and 



* Report on Zoological Nomenclature, British Association Report for 

 1842. 



