VOLUTHARPA. 199 



Mr. Gwyn Jeffreys, in his excellent " British Cohchology," 

 records the occurrence, upon the Kentish and Sussex Coasts, of 

 Buccinum undatum, having two or three opercula. "In a bi- 

 operculate specimen, procured by Mr. Rich, one of the opercula 

 is conical and borne on a cylindrical, stalk-like lobe, the other 

 being of the usual shape ; in a second specimen, one operculum 

 is longitudinally oval, with the nucleus nearty terminal (as in 

 FUSUH), the fellow operculum being placed at a right angle 

 to it." 



44 The above facts," says Dr. Paul Fischer,* 44 modify con- 

 siderably our confidence in specific and generic characters fur- 

 nished by the operculum. They at least demonstrate that the 

 absence of an operculum will not suffice for the exclusion of 

 mollusks from families the other genera of which are provided 

 with them." 



I have inserted in a former volume of the Manual an account 

 of abnormal opercula observed in Fusus and Pleurotoma^ and 

 it is well known that some species of the latter genus as well 

 as of the nearly related genus Conus are provided with opercula, 

 whilst others have them not. The duplication of opercula in 

 Buccinum undatum appears to meet a parallel in the case of the 

 Cephalopod genus Loligo, in the duplication of the internal car- 

 tilaginous pens or shells. J 



After all, the operculum furnishes generic characters of con- 

 siderable value in classification ; we can by no means afford to 

 dismiss its evidence as unreliable because it sometimes, ab- 

 normally, unsettles our long cherished (and perhaps erroneous) 

 convictions of the stability of generic and specific characters. 



" The ovicapsules of Volutharpa are not at all like those 'of 

 Buccinum, but rather like those of Busy con (= Fulgur), though 

 smaller, consisting of disk-like capsules, united by one edge to a 

 ribbon or stalk. They contain from eight to twelve embryos, 

 which attain the length of a half inch, and a shell of two whorls, 

 which, except in the absence of epidermis, essentially resembles 

 the adult. The first whorl, however, is whitish and amorphous, 



^ Jour, de Conch., 114, 1875. 

 f Vol. IT, p. 15. 

 t Manual, I, 141. 



