234 PROCEEDINGS OF THE MALA.COL0GICAL SOCIETr. 



the rules of the International Zoological Congress " a genus proposed 

 with a single original species takes that species as its type " ; it seems 

 to follow that if a genus was proposed to include two species only, 

 and if a subsequent author removes one of these species to another 

 genus, he determines the type by elimination. In this view I am 

 supported by the opinion of Dr. W. E. Hoyle. 



In the same year (1857), but three months later than the issue of 

 the part of the Messrs. Adams' work dealing with the Veneridse, 

 E. Komer published a critical review ' of this family, and this is 

 prefaced by a tabular view of the subdivisions of the Linnean genus 

 ' Vemis ' which he adopts. One of these is Gomphina, Morch, of which 

 he gives V. imdulosa as his example, for the species mentioned in his 

 scheme can only be regarded as examples, not as types. 



In 1 864-5 Eomer published a more complete revision of the Veneridse.'^ 

 In this he regarded Gomphina as a distinct group equivalent in value 

 to such genera as Mercenaria and Tapes, and he gave a detailed 

 description of its characters in Latin. In this description the part 

 relating to the hinge is specially good, complete, and diagnostic ; thus 

 he correctly describes the median tooth of the right valve as thick and 

 triangular, but says nothing about the median of the left, though the 

 anterior and posterior are described. The reason of this is that the 

 left median is solid and entire in G. undulosa, but is bifid in 

 G. dotiacina. 



In this group Eomer included four species, these being donacina, 

 Chem. ; cequilatera, Sow. ; melan<^gis, Eomer ; and wndulosa, Lam. 

 It is doubtful, however, whether the second and third are more 

 than varieties of donacina. No type was indicated by Eomer, but 

 his definition of the genus was so good that there ought not to have 

 been any subsequent misunderstanding about it. 



In 1884 Tryon regarded Gomphina as a subgenus, and made the 

 following significant remark : " Eomer describes four species and 

 considers V. imdulosa, Lam., as the type, while H, & A. Adams quote 

 V. donacina, Chem., as the only species, and place it as a subgenus of 

 Cythereay ^ Tryon evidently thought that the examples given by 

 Eomer in 1 857 should be taken as types, but was in doubt about the 

 action of Messrs. Adams. 



In 1887 Fischer placed Gomphina as a subgenus of Tapes, and gave 

 V. undidosa as an example, but this calls for no remark. 



In 1902 Dr. W. H. Dall published a "Synopsis of the Family 

 Veneridse and of the North American recent species,"* in which he 

 made many modifications of nomenclature, and proposed several new 

 names for what he regarded as sections or subgenera worthy of being 

 so distinguished. He was also careful to indicate the type of every 

 group, but did not enter into any discussion of these types, or of his 



1 " Kritische Untersuchung der Arten des MoUuskengeschlechts Venus bei Linne 



und Gmelin," Cassel, 1857. 



2 Malak. Bliitt., vols, xi and xii. 



3 " Systematic Conchology," vol. iii, p. 177. 



* Proc. U.S. Nat. Mus., vol. xxvi, pp. 335-412. 



