PHYLOGENY OF FUSUS AND ITS ALLIES. 145 



GEOGRAPHICAL DISTRIBUTION. 



All the evidence so far obtained points to Western Europe as the 

 place where the genus Fusiis originated. The most primitive species 

 of the genus yet found (F. porrcctus) is from the Eocene beds of 

 southwestern England.* The related French species (F. aciculatus) 

 is, according to all appearances, a local modification of the primitive 

 British species from which it has descended. As has been shown, 

 the other so-called French Fusi probably all belong to distinct genera, 

 as do also the species from the American Eocene beds generally re- 

 ferred to this genus. F. iinicarinatxis from France is probably not a 

 true Fusus, but may belong to the genus Faisifiisiis. In no other 

 Eocene formations have true species of Fiisus been found, so far as I 

 have been able to ascertain. Thus we are forced to regard the British 

 Eocene seas as the ancestral home of the genus. 



We have no certam knowledge of true species of Fusus in forma- 

 tions older than the Tertiary. Many Cretacic species have been 

 referred to Fusus, but for the most part it is readily seen that these 

 belong to other genera. There are. however, a few forms which need 

 more careful study to determine whether or not they are to be con- 

 sidered as true Fusi. Kaunhowen described several species from the 

 Upper (Maestrichtien) Chalk of Prussia (Gast. Maest. Kreide, pp. 

 81-83, pi. 9, figs. 9-iia; pi. 10, figs. 1-8) which, as far as the form 

 is concerned, might well be considered true Fusi. This is particularly 

 true of F. hicinctus Kaunh. Kaunhow^en compares this species with 

 Fusus (Rhopalithes) angulatus Lamarck, but this is probably merely 

 a superficial resemblance. Falsifusus (f) serratus and F. {?) unicari- 

 natiis appear to be much more nearly related to Kaunhowen's species, 

 and it is not improbable that these three species may prove congeneric. 

 Of the other species described by Kaunhowen, F. pliciferus Binkhorst, 

 F. kunmdensis, Kaunh. and F. planus Kaunh. deserve to be consid- 

 ered as possible ancestral types of Fusus. This is suggested by the 

 simplicity of the whorls, particularly in the first of these, and the uni- 

 form character of the ribs, which recalls that of the young Fusus. 

 The character of the apical whorls is, however, unknown. 



We have at present too little information to enable us to trace the 

 migrations of Fusus in time immediately succeeding the Eocene. The 

 Oligocene species known from North Germany, if true Fusi, are the 

 only European Oligocene species so far determined. 



Miocene species of Fusus are known in Europe from the Vienna 

 Basin. Strangely enough the species of this district, judging 

 from the descriptions and illustrations— and the few specimens 



♦Cossmann cites this species from "la Loire inferieiire" (Ess. de Paleocon- 

 chologie Comparee, T. IV, p. 4. 



