CERIANTHARIA. 



traction of the two sides of the mesenteries, and this is confirmed by the fact that the filaments also 

 sometimes appear to take a lateral course. The resemblance in the attachment of the acontia in the 

 two groups is thus quite superficial. 



Although I cannot therefore concur with van Beneden's view of the acontia in several 

 points, I am nevertheless at one with him provisionally (pending a closer investigation of the botru- 

 cnidae of Botruanthus) in regarding the "acontia" as homologous organs with the botrucnidae. 



Cnidorages and Botrucnidae. 



As is well known, van Beneden (1898) has given a description of some peculiar organs, to 

 which he has given the name botrucnidae. They were aggregations resembling clusters of grapes 

 formed at the aboral end of the mesenteries and on their free edge. Each grape, which when isolated 

 van Beneden called a cnidorage, was attached to the mesentery by a stalk. The cnidorages were 

 exclusively epithelial and entodermal globular formations, which contained two kinds of cells besides 

 supporting cells, namely nematocysts and mucus cells, the latter always in very small numbers. The 

 nematocysts were partly large thick-walled ones, partly thin-walled (spirocysts) larger or smaller. The 

 clustered botrucnid-grapes were in no wise distinguishable (1. c., p. 127) from the isolated ones, save 

 that the former possessed a stalk. Van Beneden then equally considered the Botrucnidae to be 

 exclusively epithelial and entodermal organs and to be homologous with the acontia, 

 on the ground that they occupy the same position as the acontia in the larval forms that bear acontia. 



Adult forms of Ceriantharia bearing botrucnidae have not however been described by van 

 Beneden, though he mentions that he has found such organs 1 ) in C. oligopodus. Two years ago 

 Torrey and Kleeberger (1909) found cnidorages in one of the Ceriantharia described by them, 

 Cerianthus benedeni- If I rightly understand Torrey and Kleeberger's descriptions they are to 

 be found on the mesenteries of the first and second cycle partly and principally on the craspedoneme 

 bunches that are on about the same level as the cnido-glandular tract ("the coiled mesenterial filaments") 

 in the third and fourth cycle, partly on more dispersed craspedouemes issuing from the border of the 

 mesentery nearer the aboral side 2 ). As regards the homology of the cnidorages Torrey and Klee- 

 berger come to the conclusion, that since the cnidorages have appeared only on filaments that 

 "correspond perfectly to the filaments figured by van H eider for C. mcmbranaceus", they cannot be 

 homologous with the acontia, which according to van Beneden "differ totally -- in position, mor- 

 phological value, structure and function -- from these filaments in C. membranaceus". 



T ) Cerfontaine the author of the name C. oligopodus, in his exhaustive account of this Cerianthid (1909) does not 

 mention the occurrence of botrucnidae. I myself, in examining a species, which was unquestionably the same as Cerfon- 

 fontaine's, failed to see any botrucnidae either. Consequently van Beneden's C. oligopodus must be a different species. 



2 ) Unfortunately Torrey and Kleeberger have apparently not made a close anatomical study either of filaments 

 or cnidorages, at any rate they give neither an anatomical description nor figures of anatomical details concerning the fila- 

 ments for which reason it is very difficult to determine the orientation of the different parts of the filaments. The ques- 

 tion is whether the "compact bunches on the mesenteries of the first and second orders" are really craspedonemes or, as 

 seems more likely, cnido-glandular tracts as in Botrucnidifer. If these "compact bunches" are really craspedouemes, then 

 these bunches are quite differently situated from those in Cerianthus mcmiranaceus and Pachycerianthus multiplicatus, where 

 they are found at the aboral end of the mesenteries. Further, I dont understand what Torrey and Kleeberger mean, 

 when they drawn a distinction between "cycles" and "orders", On p. 122 they inform us that cnidorages appear on the 

 mesenteries of the third and fourth cycles, on p. 123 that they are found oil the mesenteries of the first and second orders. 



