130 REPORT 1871. 



MM. Milne-Edwards and Jules Haime differentiate the Halysitinse as 

 follows : — 



"The corallum is compound, but its corallites unite imperfectly, and 

 constitute lamellar expansions or long fasciculi ; they are either free on two 

 sides, or arc united together by ' ea-pansions murales.' " 



The septa are small, but usually very distinct ; finally the walls are well 

 developed and aporose. 



The genera are : — Hah/sites, Fischer ; Syringopora, Goldfuss ; Tliecostegites, 

 Ed. & H. (Ilarmodites, Michelin) ; Conostefjitcs, Ed. & H. ; Fletcheria, Ed. 

 &H. 



Hall/sites. The species are invariably formed by corallites which are joined 

 on two sides, and which in transverse outline resemble links of a chain. 

 The epitheca is very strong, and unites the corallites perfectly where 

 they are in contact from the base to the calice. Septa 12. Tabulas 

 horizontal and well developed. (Silurian.) 

 Thecostegites. The corallites have septa, horizontal tabulae, and an exotheca 

 unites them, and it is more or less tabular in structure, and exists in 

 stages like the Tuhipora. In 'T, pm-mda the ccenenchyma is nearly 

 compact. (Devonian.) 

 C'onostegites. There are numerous septal s-trise, which mark also the smooth 

 and convex surfaces of the tabula). The tabulte are more or less infun- 

 dibuliform, and the epitheca unites the corallites hero and there. 

 Byringopora. The coraUum is fasciculate ; the corallites are cylindrical and 

 very long, parallel, and free laterally, except where horizontal tubes 

 connect them. The walls are well developed, and clothed with a strong 

 epitheca ; septa exist. The tabula) are infundibuliform. 

 Fletcheria. The corallum is fasciculate ; the corallites are cylindrical, close, 

 and long. The epitheca is complete ; septa exist. Tabulae horizontal 

 and well developed. No intcrcorallite tubes or expansions of epitheca. 

 Gemmation calicular. 

 It is evident that some of these genera are very slightly allied ; for in- 

 stance, Syringopora and Fletcheria, and both of them and Halysites. 



Halysites, with its stout epitheca and simple tabulae with non-tubular 

 joints, is a very definite form. 



Thecostegites should belong to the Milleporidae. 



Conostegites, with infundibialiform tabulae, is related to Halysites as Miche- 

 linia is to Favosites. 



Fletcheria is altogether aberrant. 



The Halysitince comprehend, according to this analysis, Halysites, Fischer ; 

 Btylophyllmn, Eeuss ; Conostegites, Ed. & H. 



The genera Syringopora and Fletcheria will be considered further on. 

 The subfamily of the Pocilloporinae contains the genera Pocillopora and 

 Ccenites. 



Pocillopora has septa (and my specimens show 12), which, even in fossil 

 specimens, mark the top of the tabulae. There is a columellary swelling on 

 its tabula). The ccenenchyma is very stout and thick in old portions of the 

 corallum, less so where growth has just ceased, and the ccenenchyma barely 

 exists where the corallites or calicos are developing. It is cellular at first, 

 and then fills up with calcite and other coral salts. 



Fossil forms have been described by Eeuss and myself from the Cainozoic 

 formations. 



Ccenites resembles Pocillopora in a certain density of its ccenenchyma, but 

 differs in only having three tooth-liko septa, like the genus Alveolites. 



