270 APPENDIX TO CARBONIFEROUS AND PERMIAN MONOGRAPHS. 



distinct species • while Messrs. Howse and Kirkby are still disposed to maintain the con- 

 clusions arrived at in p. 44 to 49 of my Permian Monograph. All our testiferous spe- 

 cimens of St. Morrisiana from Tunstall Hill, and casts from Humbleton, nowhere appear 

 to have possessed that immense number of closely packed spines which are observable on 

 the ventral valves of Geinitz's typical examples of St. lamellosa from Trebnitz ; and indeed 

 when I compare typical specimens of the same valve of St. Goldfusii and St. lamellosa 

 from Trebnitz sent to me by Dr. Geinitz, I am at a loss to detect any difference between 

 them ; in both the spines appear equally numerous, and to be similarly implanted, so much 

 so that it would not be possible to distinguish the two, had we not the smaller valve 

 which in St. Goldfusii is covered with spines, while that of St. lamellosa is traversed by 

 concentric laminae of growth, usually individualised and ornamented with fine radiating 

 striae. In none of the British examples of St. Morrisiana that have come under my notice 

 do we perceive that immense abundance of spines which are visible on the ventral valve of 

 St. lamellosa from Trebnitz ; on the contrary they are comparatively few, adpressed, and 

 allowing one to perceive between them fine radiating striae, while in the smaller valve we 

 do not observe those prominent laminae of growth visible in Geinitz's typical specimens 

 of St. lamellosa. It is, therefore, uncertain whether we are quite justified while placing 

 King's St. Morrisiana among the synonyms of St. lamellosa. The subject had better 

 therefore, for the present be left an open question. 



Crania Kirkbyi, Dav. Permian Mon., page 49; and Carb. Mom, PI. liv, fig. 35 — 38. 



When describing this species ? the exterior of the unattached or upper valve had alone 

 been discovered, and although most of the specimens had their external surface roughly 

 granulated, I have since been led to surmise that this appearance is perhaps due to the 

 decomposition of parts of the shell, for in two or three more solid and better preserved 

 specimens, the surface was almost smooth, or marked only by a few concentric lines of 

 growth. The apex is more or less sub-marginal, while in some specimens it is almost 

 central. It varies also much in shape, as do all Crania which live attached to submarine 

 bodies. The interior of the upper valve has also been found by Mr. Kirkby, and of which 

 illustrations will be found in Plate LIV of the present volume. So great is the resemblance 

 of some specimens of this Permian Crania to others of C. quad rata from the Carboniferous 

 Rocks of Scotland and Ireland, that I am somewhat undecided whether I should still retain 

 the denomination applied to the Permian shell. 



