FROM THE ZONE OE AMMONITES HENLEYI. 63 



XX. COEALS FROM THE ZoNE OF AMMONITES HeNLEYI, SoW. 



A great number of specimens of all sizes of a very polymorphic Montlivaltia have been 

 found on the surface of the fields at Cherrington, near Skipton, and in a water-course or 

 ditch section of the Middle Lias close by. Ammonites Henleyi, Ammonites Chiltensis, Car- 

 dinia attenuata, and Cardinia elongata, were found with the Corals. 



Family— ASTR^ID^. 



Division LiTHOPHYLLACEiE SIMPLICES. 



Genus — Montlivaltia. 

 1. Montlivaltia Victoria, Duncan. PI. XVII, figs. 1 — 10. 



The corallum grows to a great size, and generally presents a scar where it was 

 formerly attached. The shape of the corallum is very variable, and it may be short, 

 turbinate or sub-turbinate, or long and conical, or rudely cylindrical. The corallum is 

 rarely straight, and generally there is a very decided curve in it and a twist also ; more- 

 over, there is frequently a constriction just below the calice, and at this point also there is 

 generally a curve. 



The calice is either widely open or contracted and small ; it is never very deep, but 

 may be characterised either by exsert and rounded septa or by septa which dip at once 

 into a concave fossa. The outline of the calice is usually circular, and slightly compressed. 

 The margin is sharp and is formed by the epitheca. 



The septa are numerous, crowded, long, and the principal often extend to and across 

 the axial space, which is rather elongated. 



The laminse are not much thicker at the wall than elsewhere, and the dentation is 

 more distinct close to the wall. 



There are six cycles of septa, in six systems, the highest orders being very small. 



The epitheca is very dense and is strongly marked with transverse elevations and de- 

 pressions ; where it is worn away, the septal ends are seen, like costaB with transverse dis- 

 sepiments connecting them. The wall is very thin, and appears to be identified with the 

 epitheca. 



The endotheca is very abundant, thick, curved, and branching. 



Height of various specimens 5 inches. Smiths inches, S/cths inches. Breadth of speci- 

 mens 2 inches, 2T5ths inches, 2 inches. 



Locality. Cherrington, Skipton-on-Stour. 



