CONTRIBUTIONS TO THE ANATOMY OF THE BRACHIOPODA 33S' 



these the function of distending and so straightening the spirally 

 coiled, very flexible arms of this species ? 



Affinities of the Brachiopoda. — All that I have seen of the struc- 

 ture of these animals leads me to appreciate more and more highly 

 the value of Mr. Hancock's suggestion, that the affinities of the 

 Brachiopoda are with the Polyzoa. As in the Polyzoa, the flexure of 

 the intestine is neural, and they take a very natural position among 

 the neural mollusks between the Polyzoa on the one hand, and the- 

 Lamellibranchs and Pteropoda on the other. 



The arms of the Brachiopoda may be compared with those of the- 

 Lophophore Polyzoa, and if it turns out that the so-called hearts 

 are not such organs, oiie difference will be removed. 



In conclusion, I may repeat what I have elsewhere adverted to,, 

 that though the difference between the cell of a Polyzoon and the 

 shell of a Terebratula appears wide enough, yet the resemblance be- 

 tween the latter with its muscles and the Avicularium of a Polyzoon,. 

 is exceedingly close and striking. 



My attention having been called within the last two or three days,, 

 to an error in my paper on the Anatomy of the Brachiopoda,. 

 published in No. 5 of the Royal Society's Proceedings, I beg to be 

 allowed to take the earliest opportunity of correcting it. At p. 11 1 

 of that paper the following paragraph will be found : — 



"In 1843, however, M. Vogt's elaborate Memoir on Zz'«^2^/<a: ap- 

 peared, in which the true complex structure of the ' heart ' in this. 

 genus was first explained and the plaited ' auricle ' discriminated 

 from the 'ventricle;' and in 1845, Professor Owen, having appa- 

 rently been thus led to re-examine the circulatory organs of the Bra- 

 chiopoda," &c. &c. 



Now, in point of fact, though M. Vogt does describe and accu- 

 rately figure the structures called ' auricle ' and ' ventricle ' in Lin- 

 gula'^, yet he has not only entirely omitted to perceive their con- 

 nection, or to indicate the ' auricular ' nature of the former, but he 

 expressly states that the so-called ' hearts ' are " simple, delicate, pyri- 

 form sacs" (p. 13). 



I presume that my recollection of M. Vogt's figures was more 

 vivid than that of his text ; for having been unable, notwithstanding 

 repeated endeavours, to re-obtain the memoir when writing my paper, 



' Neue Denkschriften der allgemeinen Schweizeiischen Gesellschaft fiir die gesammteiii 

 Naturwissenschaften. Band VII. 



