246 G. HERBERT FOWLER. 



Though Von Koch gives no detailed description of the anatomy of 

 Caryophyllia, the following account may be inferred from his figures 

 and text (4) (6). The polyp is built on the Actinian type, consisting 

 of mouth-disc, stomatodseum, mesenteries ; the muscles of the latter 

 being arranged as in Actinia. No external body wall, its place being- 

 taken by the theca ; inner body wall of mesoderm and endoderm, 

 lining the coelenteron, and clothing the interior of the calyx, both 

 theca and septa. Mouth-disc drawn down in abnormal (?) alcoholic 

 contraction over the lip of the calyx. Entosepta and exosepta both 

 present. No mention made of tentacles. 



Of Madrepora variabilis he records, in 1880, the following facts (6): 

 Structure Actinian ; in the end-polyps of the colony six pairs of 

 mesenteries, six entosepta, and six exosepta; in the side -polyps also 

 six pairs of mesenteries, but six entosepta only. 



Von Koch has also studied Stylophora digitata in somewhat greater 

 detail (7). The form of the colony resembles that of Alcyonium 

 digitatum ; the polyps live in small calyces on the surface of the 

 colony, but the living tissues are not continued down into its centre, 

 as in Alcyonium ; the lower part of the cavity formerly inhabited by 

 the polyp being shut off by a kind of tabula as it grows upwards. 

 Over the surface of the colony lies the ccenosarc, the fleshy rind of the 

 otherwise calcareous colony, which puts the polyps in communication 

 with one another, being permeated by canals which are continuous 

 with their coelentera, and similarly lined by endoderm. The polyp 

 possesses six pairs of mesenteries, six larger tentacles, six smaller 

 tentacles, and six entosepta. There are two distinct types of nema- 

 tocyst. Longitudinal muscles occur on the mesenteries, but the small- 

 ness of the latter rendered it impossible to detect whether their arrange- 

 ment agreed with Actinia or not. 



In 1881 Dr. von Heider, of Graz, published a description of Clado- 

 cora astrcearia and CI. cespitosa (8). These species are also built on 

 the Actinian type ; and Heider describes for them the same con- 

 tinuation of the mesenteries and mesenterial spaces that v. Koch 

 mentions as occurring in Caryophyllia cyathus. I have examined 

 macroscopically and by sections CI. cespitosa in a conrpletely retracted 

 state, and can find no trace of such a condition, an observation which 

 confirms my belief that this appearance is due to partial contraction, 

 owing to the use of alcohol. There is no true ccenosarc such as occurs 

 in Stylophora, just as there is no ccenenchyme, the calyces being free 



