52 



THE ANTHOZOA 



is weak, the longitudinal muscles being less developed than the 

 transverse, and there are no muscle banners. Carlgren (14) has 

 shown that the longitudinal muscles are always found on the same 

 face in each mesentery, namely, on the face turned away from the 

 ciliated groove. In Edwardsia the opposite is the case, and it 

 is concluded that the ciliated groove of Cerianthus does not 



Fio. XXV, 



1. — Crrianihus sfilitarius, Rapp. 



2. — Transverse section through tlip stonioflical rpRion of Cerinnthu.':, showing the sulculus, s, 

 and the arrangement of the mesenteries. (After O. and R. HertwiR.) 



3. — Portion of a mesentery of Cerinnthu<! vumhrnnacens, showing the transverse muscles, 

 tin, the filament /. The Acontia-like threads, th, borne by the upper edge of the inesenterj', 

 and g, the gonads. (After O. and R. Hertwig.) 



4. — Section through the peristome of Cerianthus membranacev^, showing the longitudinal 

 ecto<leniiic muscles, M ; ec, ectodenu ; mg, niesogloea ; eti, endodenn. (After O. and R, 

 Hertwig.) 



.1.— Oral aspect of a young Arnchnactis brachioltUci, the larva of a Cerianthus, with seven 

 tentacles. (After E. van Beneden.) 



6. — Transverse section through the stomoflseal region of an older laira. The numerals 

 indicate the order of development of the mesenteries. (After Boveri, slightly altered.) 



correspond with that of Edwardsia, but is the sulculus, the sulcus 

 being absent. 



The pelagic larva shown from the oral surface in Fig. XXV. 

 5 is known as Ararhmcfis hrachiolata. It is the young form of 

 an undetermined species of Cerianthus. Fig. XXV. 6 is a trans- 

 verse section through the stomodieal region of an older larva. It 

 has nine tentacles — one small, median, and, according to Carlgren's 

 orientation, ascular ; six large and lateral ; two of unequal size, 

 but smaller than the lateral tentacles, occupy the sulcar region. 

 The section shows that these correspond to as many intermesen- 



