Davidson — On Syrmgothyris. 311 



VIII. — Perforate and Imperforate Brachiopoda. 



By Thomas Davidson, F.E.S., F.G.S., etc. 

 (PLATE XIV.) 



r answer to the observations made by Professor King in the 

 June number of your valuable Magazine, I am quite ready 

 to admit tbat several very important points in connection with 

 the shell-structure and interior aiTangements of the Spiriferid(e have 

 stiU to be determined, and I am always delighted when some new 

 light can be thrown upon the subject. 



No one has devoted as much time or shown a greater degree of 

 ability in the careful examination of the shell -structure of the 

 Brachiopoda than Dr. Carpenter has done ; and I have no hesitation 

 in reiterating that I cannot doubt the trustworthiness and accuracy 

 of his investigations. Dr. Carpenter has repeatedly shown the abso- 

 lute necessity of thin sections viewed with adequate microscopic 

 power ; and it, therefore, surprises me, that Professor King should 

 so often endeavour to throw discredit on that gentleman's observa- 

 tions, on the strength of surface-markings observed with a " hand- 

 magnifier." 



Now, with reference to Spirifera cuspidata, Dr. Carpenter assures us 

 that, after having carefully examined by the aid of first-rate instru- 

 ments the well-preserved shells of several specimens, he found in them 

 a total absence of perforations ; but that a deceptive appearance of dots 

 upon certain portions of the surface in some examples may have led 

 to the erroneous supposition that the shell had been pierced through- 

 out by canals. Several statements in an interesting paper by Mr. 

 Meek, published in the Proceedings of the Academy of Natural 

 Sciences of Philadelphia for December, 1865, made Dr. Carpenter 

 desirous of re-investigating the subject; and consequently the shells 

 of several American and British Spirifers, resembling in shape our 

 well-known Spirifera cuspidata, were assembled and carefully ex- 

 amined. Dr. Carpenter publishes the results of his investigation 

 in the July number of the Annals and Mag. of Nat. Hist, for the 

 present year. 



Some few years ago Professor Winchell discovered in the Carboni- 

 ferous rocks or " Burliagton Limestone " of Burlington, Iowa, a shell 

 undistingiushable in exterior appearance from our British examples 

 of Spirifera cuspidata, but which, from presenting certain peculiar 

 interior arrangements, had led him to propose for that and similarly 

 characterized shells the generic denomination of Syringotliyris} Now, 

 although Professor Winchell has stated that the shell of his genus 

 is fibrous and impunctate in all conditions and under high powers, 

 both Mr. Meek and Dr. Carpenter found very distinct perforations 

 in large portions of the sheU of Syringoihyris typa forwarded to 

 them by Professor Winchell himself.'- 



1 Proceedings of the Academy of Natural Sciences of Philadelphia, January, 1863. 

 ^ See Notices of Memoirs, at the end of this article (p. 315), for Mr. F. B. 

 Meek's observations on the shell-structure of Syringothyris. 



