4 CO. Whitinan 



t c-n. r,j , Tir • i EledouB Aldrovandì D . Ch. 



8. D. Eledones Wag. in ■{ „, , , ^ t i, 



_. TUT,. I {J^/edone ìììoschata Leach. 



Dicyemenneu Whit./ „ ^ ^,..,, . ,,, ti 



•^ \ %. D. Mulleri Clap. - - cirrosa Lamark. 



1,10. D. yracile Wag. - Sepia ofßcinalis Linn. 



Ofthe ten species here tabulated, Ed. Van Beneden has deter- 

 mined four , and Claparède one : of the five remaining, oue, found in 

 O. De-Filijjpi , is entirely new ; two , occurring in E. moschata , have 

 hitherto been regarded as one species . and named Dieyema Eledones 

 by Wagener, Dicyemella Wagenerihy Van Beneden; and the other 

 two, generally found together in Sepia officinalis , have likewise been 

 confounded by Wagener under the name Dieyema gracile , by Van 

 Beneden under the name Dicyemina Köllikeriana. 



With reference to naming the four species hitherto described as 

 two , it was necessary , first of all , to decide what use could be made 

 of the names already invented. After carefully considering all the State- 

 ments hearing on the question, I have no hesitation in declaring the 

 two names originating with Van Beneden synonymous with those in- 

 troduced by Wagener ; and , as in systematic zoölogy the claims of 

 priority are not to be superseded by those founded on accuracy of de- 

 scription , it seems necessary to discard this part of Van Beneden's 

 terminology. It is scarcely necessary to add, that I fully appreciate the 

 superior merit of Van Beneden's descriptions as compared with those 

 of Wagener : but usage does not allow such a discriminatiou to out- 

 weigh other considerations. Van Beneden gives no reasons for rejecting 

 the names of bis distinguished predecessor , and I fall to see on what 

 grounds such liberty could have been justly taken. Possibly the erro- 

 neous opinion , which Van Beneden appears to have entertained , that 

 Wagener iutended the name, D. Eledoties, not only for the Dicyemidae 

 of E. moschata but also those of Ociopus and Sepiola^ may, in a meas- 

 ure, explain what, under any. other supposition, must have been 

 known to be a piain violation ofthe universally recognized law of prior- 

 ity. But this explanation could not apply to Wagener's second name, 

 D. gracile^ and thus there seems no escape from the conclusion that 

 these names were discarded quite arbitrarily. It is hardly to be sup- 

 posed that the imperfection of Wagener's diagnoses, could have had any 

 decisive influence in this matter, so long as they furnished the means of 

 certain identification . Van Beneden's studies led him to the conclusion 

 that each Cephalopod has a single species of Dieyema, and this convic- 

 tion seemed to him so well founded, that he made it the corner-stone 

 of bis whole scheme of Classification, as I shall presently show. Accord- 



