464 E. ETflERIDGE, JFff., OH A LOWER-CARBONIFEROUS 



and sinus, much less number of ribs, total absence of any laminae of 

 growth, spinous asperities, or granules on the surface. 



Prom ISpiriferina insculpta, Phill., it is distinguished by the same 

 character of the hinge-line as in the former instance, greater con- 

 vexity of the ventral as compared with the dorsal valve, absence of 

 concentric lamina? of growth, and smaller area. On the other hand, 

 it agrees with S. inscidpta in the number of the ribs when that 

 species is found in its simplest form ; but these again are decidedly 

 obtuse and not angular. These points of difference can only be 

 regarded as provisional, as the discovery of further specimens may 

 bring to light varieties intermediate between the shell as here 

 figured and the typical S. inscidpta, to which, of the two species 

 mentioned, it appears to be most nearly allied. In outline, simple 

 mesial fold, and sinus it is not unlike some forms of Spirifera 

 triradialis, Phill. ; but the beak in the ventral valve is much less 

 elevated, and the shell-substance punctate. 



Locality and Position. — Fullarton Quarry, near Temple, Edin- 

 burghshire ; in shale between bands of the No. 2 Limestone ( = Hosie 

 Limestone) of the Lower Carboniferous Limestone group of the 

 Midlothian series. 



In conclusion I have to acknowledge the obligations I am under 

 to my colleagues Messrs. G. Sharman and R. L. Jack, the former 

 for supplying me with a series of beautifully executed drawings, 

 and the latter for assistance in translating certain foreign memoirs, 

 &c. 



DESCRIPTION OF PLATES XXIV. & XXV. 



Productus, sp. (Figs. 1-24.) 



Fig. 1. Portion of Encrinite stem with adherent Productus, showing the 

 spines tightly clasping it. Back view, ventral valves. 



2. A similar specimen, side view ; three spines shown. 



3. A larger and more mature specimen, front view. 



4. Three individuals clustered together ; front view, ventral valves. 

 5 A larger specimen, adhering by seven spines, front view. 



G. Interior of the ventral valve, showing the margins gradually enclosed 

 by the substance of the Encrinite stem. 



7. The same process carried a little further. 



8. The same process carried still further. 



9. Almost total disappearance of the Productus within the substance 



of the Encrinite stem. 



10. Total absorption of the Productus, and distortion of the Encrinite 



stem. 



11. Exterior of a ventral valve adhering by two and a half spines to 

 the end of a segment of an Encrinite stem. Broken spines are 

 shown round the margins of the valves. 



12. Encrinite stems with the remains of three young individuals and 

 the markings of numerous encircling spines. 



13 Exterior of the ventral valve, with the elevated umbo and groove 

 caused by the object to which it was attached. Two broken spines 

 are seen. 



14. A similar specimen. Both these figures show the concentric 

 wrinkles in a marked manner. 



