CERIANTHARIA. 



cylindrique. Disposition biseptale faisent alterner des cloisons fertiles acontiferes avec des cloisons 

 steriles privees d'aconties et portant des fils mesenteriques sur leur craspedes. Musculature endoder- 

 niique a peine represente. Paroi de la colonne epaisse et consistente, a cause du developpemeut pris 

 par la musculature lougitudiuale et par la mesoglee." In his description of the type P. bcnedcniRo\\\e 

 adds the following concerning the filaments and acontia, after mentioning that filaments (craspedes) are 

 found on all mesenteries, except the feeblest. "Seulement et en alternance les unes ont des fils mesen- 

 teriques sur leur craspedes et les autres n'en portent point. Les cloisons ainsi privees sont fertiles, 

 denuees de fils mesenteriqnes, elles possedent par centre des aconties sur une assez grande part de 

 leur extremite inferieure; leur serie debute par S 3 et continue par les numeros d'ordre impaire S 3 S 7 S 9 ". 



According to this the fertile mesenteries would bear "acontia" whilst the sterile mesenteries 

 would be provided with craspedonemes. If Roule's view were correct, Pachycerianthus would thus 

 be a genus coming under Acontiferae. But this, I think, can hardly be the case, as I suspect that 

 Roule had not clearly grasped the true nature of an "acontium". My supposition is supported too 

 by the expression of Roule's just quoted, that the acontia are found "sur une assez grande part de 

 leur (des cloisons) extremite inferieure". As far as at present known, the acontia are never distributed 

 over the mesenteries in such a way; it seems likely therefore that Roule has confounded them with 

 the craspedonemes of the region of the ciliated tracts. Pachyccriantlms bcncdeni might thus stand as 

 the type of a genus included in the first Ceriantharia family, that which does not possess acontia nor 

 botrucnidae. To this genus would belong P.fimbriatus Me. Murrich, C.lloydii Gosse and others (see 

 tables below p. 44 47) but not C. oligopodus, for which a new genus must be set tip, unless a larval 

 genus is taken for this form, which is not likely to be so good, as the development of the species 

 and consequently the connection between the larval and the full-grown form is not quite certainly 

 known. I call this genus Arachnanthus and take as its type A. oligopodus (Cerf.), as this species is 

 the best known. 



I now suggest therefore a different division of Ceriantharia, based on a thorough anatomical 

 study of different species. Besides the genus Arachnanthus just mentioned, we now institute two 

 more new genera Botrucnidifer and Ceriantheopsts (Types B. norvegicus n. sp. and C. americanus Verr.). 

 Very likely this division may also have to be modified later when a larger number of species of 

 Ceriantharia have passed under close anatomical investigation. But by starting from those features 

 which I have indicated in the diagnosis of families and genera below, it may be possible gradually 

 to secure a satisfactory classification of Ceriantharia. My suggestion for the division of Ceriantharia 

 is of the following nature. 



Fam. i Cerianthidac. 

 Ceriantharia without "acontia" and without cnidorages and botrucnidae. 



Genus i. Pachycerianthus Roule. 



Cerianthidae whose 2nd couple of protocnemes are short, sterile and provided with an extremely 

 well developed region of the cnido-glandular tract. Arrangement of metacnemes (= deuterocncmes 

 Me. Murrich) in each quartette M,B,iu,b, (1,3,2,4) more or less distinct. 



