VOLUTHARPA. 199 



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

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

 Buccinum midatum^ having two or three opercula. " In a 1)1- 

 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 longitudinall}^ oval, with the nucleus nearly terminal (as in 

 Fus'us)^ the fellow operculum being placed at a right angle 

 to it." 



'■ The above facts," sa3^s Dr. Paul Fischer,* " 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 

 moUusks from families the other genera of w^hich are provided 

 with them." 



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

 of abnormal opercula observed in Fusus and Pleurotoma^f and 

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

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

 whilst others have them not. The duplication of opercula in 

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

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

 tilaginous pens or shells. | 



After all, the o))erculum furnishes generic characters of con- 

 siderable A'alue 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 ovicai)sules of Vohilharpa are not at all like those of 

 Buccinum^ but rather like those of ^«.s'i/con (= Fulgur) ^ihowgh 

 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. 

 t Vol. II, p. 15. 

 X Manual, I, 141. 



