7 < 



9 -^ 



ACTINOZOA. 207 



' Sclerenchyma reticiilate. The- 

 (fse not distinct from the sur- 

 rounding ccenenchyma. . Family 1 1 . Poritid^. 

 Sclerenchyma simply porous. 



Thecse distinct. . . . Family i2. MADEEPOEiDiE. 



Synapticulae present. No dis- 

 sepiments. . . . . Family 13. Fungidje. 



Synapticulse absent. . . .... 9 



Dissepiments in general numer- 

 ous. Ccenenchyma absent, 

 or formed only by the deve- 

 lopment of the cost* or epi- 

 theca. .... Family 14. AsTEiEiD^. 



Dissepiments few or absent. . . . . . .10 



r Ccenenchyma compact, abun- 

 10 < dant. .... Family 15. Oculinid^. 



[_No ccenenchyma. . . . Family 16. Tuebinolid^. 



In addition to those here defined, Milne Edwards 

 has distinguished four other families oi Aporosa, 

 which inosculate, so to speak, between the primary 

 groups just mentioned. The first family, Das- 

 midoB, includes but a single genus, closely related 

 to the Turbinolidw, from which it differs in the 

 peculiar modifications of its septa. Each of these 

 is represented by three vertical laminae, united 

 only along their external margin. A second 

 family, Stylophoridce, appears as a transitional 

 group between the Oculinidw and Astixeidce, As 

 in the former, there is a well-developed ccenen- 

 chyma and few dissepiments ; but, on the other 

 hand, the surface of the ccenenchyma is echinu- 

 late, while it is smooth in the Oculinidce, and the 

 thecse of the corallites do not, as in that family, 

 increase endogenously, so as almost to obliterate 

 the loculi. Another osculant family, Echino- 

 poridcB, still more closely resembles the ^s^roe^cZa^, 

 differing therefrom chiefly in the possession of a 

 foliaceous, basal ccenenchyma. But one genus 



