178 



G. W. SHRUBSOLE EURTEER NOTES ON 



13. Further Notes on the Carboniferous FENESTELMDiE. By George 

 Wm. Shritbsole, Esq. F.G.S. (Read January 19, 1881.) 



In a former communication to the Society I endeavoured to show 

 that, as the result of a careful comparison of the existing individual 

 forms, as figured by previous describers, with some tolerably 

 perfect specimens in my own possession, it would be necessary to 

 redeseribe the species of Fenestetta and considerably reduce their 

 number. I accordingly append a redescription of the more promi- 

 nent species ; but before introducing that, it will be necessary to say 

 something about the foundation of the genus Fenestella, since it can 

 readily be imagined that the same causes which have thrown con- 

 fusion into the species, have tended also to obscure the genus — 

 namely the fragmentary and imperfect state of the specimens ex- 

 amined, and the want of attention to the stages of individual growth 

 and other details. Accordingly I find the existing descriptions of the 

 genus Fenestella inaccurate in many essential details. The genus 

 has been defined by several palaeontologists, but each time with 

 reference to the fossils of a particular period; and no one description is 

 sufficiently comprehensive to embrace all the members of the family 

 Fenestellidae as they occur in the various Palaeozoic formations. A 

 fresh description of the genus therefore appears to be desirable. 



"Without entering upon a full history of the genus Fenestella, I 

 may mention that the first to describe it as such was Lonsdale, in 

 1839*, who adopted the name from the MS. of Miller of Bristol, 

 who had been engaged on a work on the Corals of the Mountain 

 Limestone, which he did not live to complete. He gave the name 

 Fenestella to the lace corals. Fenestella Milleri of the Silurian is 

 so named after him. Lonsdale twice defined the genus — first in the 

 ' Silurian System,' and again in the ' Geology of Russia 'f. In the 

 former he restricted the cells to one row on each side of the keel : 

 and in the latter he placed no such limit to the order or arrangement 

 of the cells ; hence it included Polypora, Retepora &c, in fact all the 

 fenestrate species. His otherwise elaborate definition was also 

 faulty to the serious extent that he described the appearance of a 

 common incrusting coral as the mature growth of the Fenestella. 

 This I explained in a recent communication to the Society. 



Phillips next in order of time (1841) gave a very good description 

 of the genus, so far as relates to the Devonian group^ ; but much of 

 its details are not applicable to the Silurian group. 



Prof. M'Coy, in 1844 §, restricted the genus to forms with two rows 

 of pores on the branches, so as to include only the true Fenestella;. 

 The pore-cells he limits to the external face, whereas in the majority 

 of the species they are on the inside of the polyzoary. He further 



* Murckison's ' Silurian System,' p. 677. 



t Geology of Russia, vol. i. Appendix A, p. 629. 



I Palaeozoic Fossils, pp. 22, 23. 



§ M'Coy 's Syn. Carb. Foss. Ireland, p. 200. 



