Volume IV. October, i8go. Number 2. 



JOURNAL 



1>K 



MORPHOLOGY 



CONTRIBUTIONS ON THE MORPHOLOGY OF 

 THE ACTINOZOA. 



I. THE STRUCTURE OF CERIANTHUS AMERICANUS. 



J. PLAYFAIR McMURRICH. 



The genus Ceriantkus was established in 1829 by Delle 

 Chiaje for the Mediterranean form which we now know as 

 C. membranaceus, it having been originally described by Spallan- 

 zani as Tubularia membra7iacea. Until 1854, however, no thor- 

 ough study of the internal structure was made, but in that year 

 appeared the excellent memoir of Haime ('54). In this it is 

 shown that each "loge" has communicating with it two tenta- 

 cles, one belonging to the marginal, the other to the oral group. 

 Haime also described the arrangement of the mesenteries, show- 

 ing that two mesenteries, the cavity between them forming a 

 continuation of the " fossette gastrique " (siphonoglyphe), ex- 

 tend the entire length of the body to the terminal pore, while 

 the rest stop at a short distance below the internal opening of 

 the stomatodaeum, and are unpaired, although they are alter- 

 nately slightly unequal in length and prominence. Haime de- 

 scribed, too, the hermaphroditism of this species, and gave an 

 incomplete account of some stages in its development. His 

 account of the -histology was, however, by no means exhaustive, 

 though admirable, when the facilities for such work at that time 

 are taken into consideration. 



For twenty-five years nothing further was done towards the 



