the whole colony hard and soft parts together, the word Coenosteum to signify the hard coral 

 skeleton only. The word Coenosarc refers to the system of canals and superficial ectoderm 

 connecting the zooids of the colony, the words Gastrozooid and Dactylozooid refer to the soft 

 parts of the zooids only. With reference to the word "Coenenchym" frequently used by writers 

 on Madreporaria, Hydrocorallina and Alcyonaria a few remarks here seem appropriate. 



The word seems to have been introduced by Milne Edwards and Haime and the 

 following sentence from their chapter of general considerations on the organisation of corals 

 explains clearly the sense in which they used it ] ). "Il existe par conséquent la un tissu commun 

 ou eoaienchymc qui précède 1'existence des individus et qui joue un róle considérable dans la 

 constitution du polypier, ainsi que nous Ie verrons par la suite". 



The word is used in a similar sense by Külliker 2 ) who speaks of de Lacaze Duthiers 

 discovery that the axis of the precious coral is formed by "einer Verkalkung der inneren 

 Lagen des Coenenchyms" and by many other writers. 



Originally then the word referred to soft tissues only. Writers on Alcyonarians at the 

 present day use it for extra-thecal parts of a colony, i. e. hard spicules and soft tissues 

 together, exclusive of the solidified axis. Writers on Madreporaria have however come to use 

 the word in a different sense altogether so that we read in a recent paper on Madreporaria. 

 "By universal acceptation coenenchyme is the calcareous deposit originating from the coenosarc" 3 ). 

 This is neither historically nor philologically correct. The sense in which the word Coenenchym 

 should be used and is used by us in this memoir is as the expression for the superficial hard 

 and soft parts beyond the limits of the zooid pores. 



Stylaster Gray. 



The genus may be defined as follows : 



Coenosteum arborescent usually flabelliform. Pores in regular cyclosystems only. Style 

 in gastropores and dactylopores. Dactylozooids can be only partially retracted. Ampullae usually 

 prominent in both male and female stocks. Male gonophore with an endodermic spadix, four 

 to five gonophores in each male ampulla. 



This definition differs from that of Moseley in several respects. The difficulty which he 

 originally pointed out of separating Stylaster from Allopora has not been overcome. Speaking 

 generally the colonies of Allopora are more robust in habit and do not show such prominent 

 male ampullae at the surface as are usually found in Stylaster. The male and female gonophores 

 of the two genera are very similar in detail but, from the limited number of forms investigated 

 at present, it appears probable that in the species of Stylaster there are more gonophores 

 (4 — 5) in each male ampulla than there are in Allopora. And as the male gonophores are 

 more deeply seated in Allopora than in Stylaster the tubular spout of the testis is longer and 

 more definite in the former than in the latter genus. Moseley thought that a difference might 



1) Milne Edwards and Haime. Hist. Nat. des Coralliaires. t. 1, p. 29. 



2) A. Kölliker. Icones Histiol. p. 117. 



3) J. E. Duerden. Mem. Nat. Acad. Sci- VIII, 1902. 



