Palaozoic Corals and Foraminifera. 



127 



giving a very irregularly angulose section to the stem ; surface 

 smooth ; internal structure as given in the generic character. 



Rare in the carboniferous limestone of Derbyshire. 

 [Col. University of Cambridge.) 



Heterophyllia ornata (M'Coy). 



^p. Char. Stems subcylindrical^ long, flexuous, averaging \\ line 

 in diameter, with about sixteen narrow, subequal, longitudinal 

 ridges sharply defined, and separated by flat spaces rather 

 wider than the ridges they separate, the ridges are set with 

 small round tubercles more than their own diameter apart ; 

 surface very minutely granulose : internal structure as in 

 generic character ; horizontal section, lamellBe about fourteen 

 at the margin, 



Kather rare in the carboniferous limestone of Derbyshire. 

 {Col. University of Cambridge.) 



Siphonodendron (M'Coy), n. g. 



Gen. Char. Corallum of variously aggregated, branching, cylindri- 

 cal or elongate-conic stems; young branches produced by lateral 

 buds ; outer wall thin, 

 lined by two or three 

 rows of small vesicular 

 plates forming a narrow 

 outer vesicular area in 

 both sections ; terminal 

 cups deep, lined by 

 numerous vertical la- 

 mellae, alternately larger 

 and smaller, and having 

 in the bottom a small, 

 prominent, tubular axis : 

 vertical section shows a 



small, central, persist- Recent Lithodendron. 

 ent, siphon-like tube «• Mode of growth 

 or axis, which pierces 



"r— 



throug:h a series of long, j 



Siphonodendron. 



Mode of growth 

 and vertical sec- 

 tion. 



and vertical sec- 

 tion. 

 Horizontal section. 

 conical or dome-shaped 

 transverse diaphragms occupying the greater part of the 

 width of the tube, the convexity upward, forming in this sec- 

 tion lines diverging downwards and outwards from the axis, 

 till they reach the narrow external cellulose layer on each 

 side : horizontal section shows the small tube-like axis, sur- 

 rounded usually by a few thin concentric lines which are the 

 edges of the conoidal diaphragms cut through by the section ; 



