The Actiniae of the Plate Collectiou. '295 



mesenteries I found occasional departures from the normal, one 

 specimeii, for iiistance, possessing tliirteen perfect pairs and only 

 eleven imperfect pairs of the third cycle, one of the pairs 

 of this cycle having apparently broadened sufficiently to reach the 

 stomatodaeum. 



I could not detect the slightest trace of an ectodennal muscu- 

 lature or nerve layer in the column wall, whose epithelium was in 

 an adrairable State of preservation. 



DuERDEN (1900) has found that the mesenterial filaments of 

 C. nijjrc'ia lack the ciliated streaks and regards this peculiarity as 

 heing- of sufflcient importance and constancy to be worthy of a place 

 in the definition of the genus. Carlgren also (1900) notes the ab- 

 sence of the streaks in C. glohulifera. In the present species I find 

 in sections which pass through the upper portions of the filaments 

 distinct indications of the trefoil appearance which is associated with 

 the presence of the streaks. The histological preservation of the 

 internal epithelia was not, however, sufficiently perfect to allow of 

 a positive Identification of the lateral processes with ciliated streaks, 

 but thej'' were supported by mesogloeal processes and the nuclei 

 of their epithelium were more densely crowded than in the median 

 process, two peculiarities which correspond with the conditions in 

 typical ciliated streaks. In a specimen of C. viridis, which I owe 

 to the kindness of my friend and coUeague Professor A. C. Haduon, 

 I have observed a similar structure in the uppermost portions of the 

 filaments, and although the cells of the lateral processes are hardly 

 as slender and closely set as in typical ciliated streaks, yet there 

 seems to be no doubt as to their homology with these structures. 



Order Zoantharia Carlgren, 1899 



Zoantheae AuCTT. 



Zoanthinaria Van Beneden, 1898. 



Anthozoa sometimes solitary, but more usually forming colonies ; 

 the polyps destitute of a corallum, but frequently encrusted with 

 calcareous or siliceous particles. The mesenteries arranged in pairs, 

 of which two sets may be recognized; the first set consists of six 

 pairs, two of which, situated at the extremities of the sagittal axis 

 and having their longitudinal muscles on the exocoelic faces, con- 



Zool. Jahrb., Supplement. Bd. VI. (Fauna Chilensis. Bd. III.) Heft 2. 20 



