44 E. J. CHAPMAN ON THE 



Fam. 2. Amphxidœ : — Corallites tubular or reed-like, typically with short or marginal 

 septa and extended tabulœ. 



Amplexus, Sowerby, Sil., Dev., Carb. 

 CalophijUum, Dana (including Cyalhophylloides), Sil. 

 Chonophyllum, E. & H., Sil., Dev. 



Fam. 3. Zaphrenlidœ : — Corallum simple, turbinate or horn-like, with well developed 

 tabulae and septa. 



Group A. — Connculaii (simple, horn-like forms) : 



Zaphre/itis, Raf. (including Anisophyllum and Penlaphyllum), Up. Sil., 



Dev., Carb. 

 Ptycophyllum, E. & H., Sil., Dev. 

 Streptelasma, Hall. Under this genus, the forms of Zaphrentis with marked 



pseudo-columella may be appropriately placed. Sil. 



G-roup B. — Columniferi (with distinct columella) : 



Lophophyllum, E. & H., Dev., Carb. 



Group C. — Cruciferi (primary septa forming a distinct rectangular cross) ; 

 Phryganophyllum, de Kon., Carb. 



Group D. — Bi-formes (septa showing a twofold mode of arrangement) : 



Menophyllum E. & ÏÏ., Carb. 



§ 5. Vesiculo-Stellata. 



This section is more or less closely connected with section 4, but is distingviished 

 especially by the contracted dimensions of the tabulte, and the replacement of the outer 

 portion of these by an area of vesicular tissue. Hitherto, many genera of these corals 

 have been made to include both simple and compound forms, as well as types of very 

 dissimilar configuration ; but in the present distribution I have ventured upon an inno- 

 vation in this respect — believing, from the examination of numerous examples, that a 

 generic separation of the compound tesselated forms on the one hand, and the sub- 

 aggregated, reed-like and cylindrical types on the other, from the essentially simple forms, 

 is warranted on natural grounds, and is conducive to a more ready determination of 

 genera, as well as to clearer and sharper definitions. 



In the present distribution these vesiculo-stellate corals are arranged under four 

 families, comprising : (1.) Cyathophyllidce, distinguished by the absence of a columella 

 and by the absence of a distinctly cruciform arrangement of septa ; (2.) Lonsdalidœ, in 

 which a distinct columella is present ; (3.) Stauridœ, characterized by the primary septa 

 forming a distinct rectangular cross ; and (4.) Halliadœ, with distinctly twofold arran- 

 gement of septa. 



