irkdalp: : ox misused genkric names. 297 



the generic nomenclature of this group, which was rectified by 

 Fischer in 1866." 



According to Ball's argument Fistulana, as used by him, would 

 be nameless, but before moving in tliis matter the genus name 

 Gastrochcena must be re-investigated. This name was inti'oduced by 

 Spengler in the Nye. Saml. Vidensk. Selsk-Skrifter (Kjoben.), 1783, 

 p. 174. Three species are named and figured: p. 179, Gastrochcena 

 mumia, pi., figs. 3-6 ; p. 180, Gaslroch(Bna cuneiformis, pL, figs. 8-11 ; 

 p. 182, Gadrochcena cymhium, pi., figs. 12-16. No type was named, 

 but the predominate species was G. mumia. Five years afterwards 

 lletzius (Diss. Hist. Nat. Nov. Test. Gen., 1788, p. 19) proposed 

 ChcBna for tlie same series. I suggest that Bruguiere's genus was 

 coequal, but that does not matter. Spengler in 1793 used Retzius' 

 name. Whether Cii vior's or Lamarck's action with regard to Fistulana 

 affect Gastrochcena does not now concern us. They do not seem to 

 have fixed a type of Gastrochcena, but rather seem to have ignored it 

 or wished to discard it. 



Gray in the Proc. Zool. Soc, 1847, p. 189, designates 

 Ghana, a, lletz., 1788. Ch. mumia. 



Gastrochcena, Spengler, 1780. Mya duhia. 

 If the first designation were available, then that could be used as 

 type of Spengler's genus, because Chcena was sim])ly a substitute 

 name ; the second designation was invalid, as Mya duhia was not one 

 of the Spenglerian species. 



However, in the Gen. E,ec. Moll., vol. ii, pp. 334-6, June, 1856, 

 H. & A. Adams used Gastrochcena, noting as synonyms Chcena, Ketzius, 

 and Fistulana, Lamarck. They gave as example G. mumia, Spengler, 

 and wrote: "The curious shell on which Spengler founded this 

 genus is generally knawn under the name of Fistula)ia data, Lamarck ; 

 it is also the type of the Chcena of Retzius." 



This statement should be taken as absolutely fixing the type of 

 Gastrochcena, and this name will displace Fistulana of recent authors, 

 which is preoccupied, and we will revert to Rocellaria for the species 

 recently known as Gastrochcena, but which for many years carried that 

 name, and with wliich even we of the youngest school are familiar. 

 The names would be then : 



Gastrochcena, Spengler, 1783. Type, G. mumia, Spengler. = Fistu- 

 lana of recent writers. 

 Rocellaria, Blainville, Diet. Sci. Nat. (Levrault), vol. Ivii, 1828 

 (January 10, 1829), p. 244 (fxFleuriau de Bellevue MS.). Type 

 (by monotypy) G. modiolina, Lamk. = Mya duhia. Pennant. 



Bela, Gray. 



As a text for a sermon on " Pleurotoinoid " nomenclature Bela will 

 do as well as any other name. Probably every conchologist will agree 

 with me that the family known so long as Pleurotomidse is probably 

 the most difficult of any to study in the whole class. Reasons 

 are not difficult to provide for this : numerous in species, though 

 few in specimens, and similarity of design, all tend to produce complex 



