King — On Perforated Spiriferidce. 255 



lished long ago.^ But it remains a secret with Dr. Carpenter, why 

 he has been so remarkably reticent on the errors — grave ones too — 

 committed by himself in connexion with the histology of these 

 same shells.^ And why Mr. Davidson should have thought it prudent, 

 or necessary, to mention my name in his testimonial of " most implicit 

 belief" in favour of Dr. Carpenter, appended by the latter to the 

 letter referred to, is another matter which requires at least a passing- 

 notice. 



Cyrtina heteroclita. — From what has been published of late years 

 respecting this species, and the genus in which it has been placed by 

 Mr. Davidson,^ justice to myself requires me to make the following 

 statement. — The principal portion of the apophysary system of the 

 shell under notice was first made known, I believe, by myself many 

 years since. I described the large valve as possessing a median 

 plate, to which are attached, one on each side and at a little distance 

 from its free margin, the dental plates, so as to form an arch-shaped 

 process, similar to that in Pentamerics, CamaropJioria, and some other 

 genera.* I also announced that its valves are distinctly perforated.^ 

 Any one referring to Davidson's British Fossil Brachioj)oda, the 

 Sandberger's Die Versteinerungen in Nassau, and certain other works, 

 in which Cyrtina heteroclita is described, jDublished since my "Mono- 

 graph " appeared, will fail to find a single sentence indicating that 

 its internal structure and histology had been previously described by 

 myself. 



Mr. Davidson has placed Phillips' Spirifer septosus in his genus 

 Cyrtina ; but he appears to have overlooked the question, as to 

 whether, or not, it is perforated. Suppose this species to be im- 

 perforate : How are we to reconcile its being placed congenerically 

 with Cyrtina heteroclita, which has well-marked perforations ? 

 Should Spirifer septosus prove to be unprovided with a canal-system, 

 I would, in this case, have no hesitation in removing it from Cyrtina ; 

 for, although I am no believer in the view which assigns the function 

 of respiration to the perforations, I attach sufficient importance 

 to them to consider that they form a good generic character." 

 Perhaps they are even diagnostic of a family, or sub-family ? 



As the canal-system of Cyrtina heteroclita has only been imper- 

 fectly illustrated by other observers, I have given a transverse 



1 See " Ann. and Mag. Nat. Hist.," 2nd Series, Vol. xviii. April, 1856. 



- See " Eeader," August 19th, 1865; and the paper cited in the last foot-note, 

 with reference to the " thin sharply-folded micaceous plates " (now admitted by 

 Dr. Carpenter to be fibres, or prisms), forming the shell -substance of the Pallio- 

 branchiata ; also "Ann. and Mag. ISat. Hist.," 2nd [Series, Vol. xix. p. 214, etc., 

 respecting the "mere pits upon the internal surface" of Rhyncliopora Geinilziana 

 (now proved, as I originally considered them, to be perforations of the canal-system, — 

 See, op. cit., 2nd Series, Vol. xvii. p. 506 ; 3rd Series, Vol. xvii. p. 230-233). 



3 Is this species the type of Cyrtina ? 



* See " Ann. and Mag. Nat. Hist.," Vol. xviii. p. 86, 1864 ; and pre-cited 

 "Monograph," p. 68, 123, and 124. 



^ See my " Monograph on Permian Fossils " (Pal. Soc), p. 126. 



6 In a memoir, in course of publication, " On the Histology of the Test of the 

 Palliobranchiata," I have given some facts and evidences which are strongly opposed 

 to the respiration view. 



