A Contribut. to the Embryol., Life-higtory, and Classiticat. of the Dicyemids. 5 



ing- to this view, the species of Dicyema woiild be determined the moment 

 that of the Cephalopod became known, audvice versa. Itìs evident 

 therefore that Wagener gave, in namiug the Cephalopod, ali that was 

 actually required by Van Beneden's system for Identification. I find no 

 difficulty in recognizing in two of Wagener's figure« the two species 

 of Dicyema which I bave found in E. moschata ; and precisely the same 

 may be said of two figures given by Van Beneden (PI. 1, fig. 4 and 

 PI. 2, fig. 1). 



The grounds for not adopting the names I). Wageneri and D. Köl- 

 likeriana are sufficieutly obvioiis , without urging the additional fact 

 that Van Beneden has , in both cases , confounded two species under 

 the same name. 



With regard to the prior designations of Wagener , the discovery 

 that each covers two species, gives me a discretional right of rejecting 

 or retaining them. Although I can no longer employ them in their ori- 

 ginai sense, stili it seems possible to make use of them without causing 

 any appreciable amount of confusion in nomenclature ; and this course 

 commends itself as one which accords best with the deference due to an 

 eminent authority , and as one which smacks least of the practices of 

 the reckless system-smasher and name-monger. 



The course adopted with reference to the three generic names in- 

 troduced by Van Beneden, requires a brief explanation. It was impos- 

 sible to retain these names without assenting to the conclusions which 

 formed the basis of Van Beneden's system of Classification and deter- 

 mined bis method of naming; for the names, method, and ideas cleave 

 to each other with such logicai coherence that they must stand or fall 

 together. As these conclusions were not confirmed, but plainly contra- 

 dicted by facts to be recorded in this paper, they had to be abandoned, 

 and with them the generic names founded on them. It seems therefore 

 proper to state precisely what these conclusions are , and how they 

 stand related to the names under consideration. 



With reference to the first point, the following citation is made : 



»Mes études sur ces organismes me mettent en mesure d'affirmer 

 que chaque Céphalopode a sou espèce particulière de Dicyema. Mais 

 les espèces qui habitent des Céphalopodes proches parents sont beau- 

 coup plus voisines que celles qu'hébergent des Céphalopodes appartenaut 

 à des familles dififérentes. De là la necessitò d'établir plusieurs coupes 

 génériques.« (1, p. 8.) 



In harmony bere with , a system of names is invented which runs 

 parallel with that of the Cephalopoda. The genus of the parasite coin- 



