CERIANTHARIA. 



Our knowledge of the Ceriantharia dates from 1784 when Spallanzani gave a brief 

 description of the form now generally known as Ccrianthus mcmöranaceus, regarding it as a 

 somewhat aberrant Tubularia, to which genus Rapp (1829) also referred C. solitarius, first 

 described by him. In 1804 Renier, according to Meneghini (1847), had described C. membra- 

 naccus as Adinia cylindrica, thus associating it with the Actiniaria; in 1828 the same author 

 redescribed it as Moscata rododattila-, in 1830 della Chiaje assigned it to the genus Cerianthus 

 under the name C. cornucopi<?\ and in 1852 Milne-Edwards and Haime recognized a family 

 Cerianthidae, distinguished from the other Actiniaria by possessing a rounded aboral pole and 

 including Ilyanthus as well as Cerianthus. It was not until 1854, however, that Haime gave the 

 first detailed account of the anatomical peculiarities of a Cerianthid, showing that it possessed 

 many features distinguishing it from other Actiniaria, notably the arrangement of the tentacles 

 and the occurrence of the mesenteries in couples instead of in pairs. Von Heider (1879) enlarged 

 on Haime's observations, principally by the discovery of sterile mesenteries alternating with the 

 longer fertile ones which alone Haime had observed, and the brothers Hertwig (1879) confirmed 

 this discovery and added the important conclusion that in all probability the formation of new 

 mesenteries takes place only at one region of the body, namely, on either side of the dorsal 

 median line. Correlating the results of their studies, the Hertwigs recognized the fundamental 

 distinctness of the members of the genus Cerianthus from the other groups of Actiniaria, and 

 in 1882 R. Hertwig established for them and their cono-eners the order Cerianthese. 



o 



With the recognition of the distinctness of the Cerianthece arose the question of their 

 phylogenetic affinities to the other orders of Anthozoa. As already stated, the Hertwigs had 

 concluded on anatomical grounds that new mesenteries appeared in couples in a single mesenterial 

 chamber, namely, that which lies opposite the single large siphonoglyph, and von Koch (1SS0) 

 arrived at the same conclusion from observations made upon young larvse of C. mcmbranaceus. 

 The evidence brought forward by Vogt (1880) and H. V. WlLSON (1888) served to confirm 

 the Hertwigs' conclusions, and the matter was finally settled by the observations of Boveri 

 (1889) and myself on Arachnactis l ). 



At least it was settled so far as the development of all couples beyond and including 



1) Kor a discussion of the systematic position of A. brachiolata see latei', under the genus Arachnactis. 



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