94 REPORT — 1856. 



Remarks on the Anatomy of the Brachiopoda. By Albany Hancock. 



Having been engaged for some time past in investigating the structure of the 

 Brachiopods, I propose laying before this meeting of the British Association the 

 results attained up to the present moment, especially on two or three points, to which 

 my attention has been more particularly directed, and on which there exists some 

 diversity of opinion among anatomists. 



So far back as 1852 I had dissected H'aldheimia Australis a.ndTerelratulina cajmt- 

 serpentis, and was struck by the peculiar appearance of the organs commonly deno- 

 minated hearts, which seemed very unlike any molluscan heart that I had ever seen. 

 On attentive examination, it became evident that they gave off no arteries as they 

 had been described to do ; and, moreover, that their apices, from which the arteries 

 were stated to pass, appeared to open externally. I was therefore, and for other 

 reasons, inclined to consider the so-called hearts oviducts. 



At the same time I examined, with considerable care, the alimentary tube, my 

 attention having been particularly drawn to this part by Mr. Woodward ; and failed 

 to demonstrate an anal outlet, though I was disposed to believe in the existence of 

 a minute anal puncture ; and thought that the refuse of digestion might make its 

 escape by the foramen of the pedicle. Howsoever this might be, it was quite obvious 

 that no anal aperture was situated in the pallial chamber as described by Professor 

 Owen. I also examined the muscular apparatus, and likewise the nervous system ; 

 and the complicated structure of the mantle, I found, invited further investigation. 



Other and more urgent matters, however, at that time claimed my attention, and 

 all further inquiry into the structure of the Brachiopods was necessarily postponed. 

 The results at which I had arrived were, nevertheless, partially made known, and 

 have, to a considerable extent, been substantiated by the more recent investigations 

 of Mr. Huxley, who in 1854 published a very interesting paper on the anatomy of 

 the Brachiopoda in the ' Proceedings of the Royal Society.' In this paper the author 

 arrives at the conclusion, that in Waldheimia and Rhynchonella there is no anus at all, 

 but that the intestine terminates in a blind sac ; that the so-called hearts give off no 

 arteries, and that they possibly open externally. Mr. Huxley also describes, for the 

 first time, a system of ramified peripheral vessels, and two or three pyriform vesicles, 

 one of which is attached to the stomach, and is in connexion with a series of " ridges " 

 and "bands." Some of the "ridges " are stated to pass from the so-called hearts 

 to the genitalia ; and the whole apparatus is supposed to be a portion of the circula- 

 tory organs. 



It is then mainly in relation to these points, respecting the vascular and alimentary 

 systems, raised by Mr. Huxley and myself, that there is a difference of opinion. 

 Professor Owen maintaining the existence of an anal aperture situated in the paliial 

 chamber, and that the so-called hearts are true vascular centres propelling the blood 

 through arteries to the various organs. The opinion of this distinguished anatomist 

 demands the utmost deference ; and it is on no slight grounds that I have ventured 

 to dissent from it in this instance, doing so only after the most diligent examination 

 that it was possible to give to the subject, and when to doubt longer would have 

 been to disregard the evidence of my senses. The greatest caution was forced upon 

 me, not only by the respect due to authority, but likewise because analogy strongly- 

 favoured the views of the learned Professor respecting an anal aperture. And here 

 it must be stated that I should never have been able to enter upon this subject with 

 any chance of success, had I not had at my command an ample supply of specimens. 

 I have therefore to express my obligations to Dr. Gray, Mr. Huxley, Mr. Wood- 

 ward, Mr. Davidson, Mr. M'Andrew and Mr. A'der; as it is to the liberality ot 

 these gentlemen that I am indebted for the specimens used upon the present 

 occasion. 



First, with regard to the so-called hearts : these are two in number in the Tere- 

 bratulidfB ; they are composed of two portions, which have been denominated respect- 

 ively auricle and ventricle. The former portion is suspended by a membrane in 

 the visceral chamber, and resembles the mouth of a trumpet with the inner surface 

 laminated in a radiating manner. The other portion is tubular, arched and tapering, 

 and is imbedded in the thickness of the anterior wall of the visceral chamber, passing 

 diagonally through it. On reaching the surface, the apical extremity opens into the 

 pallial chamhtr. The whole organ may be looked upon as a tube, constricted a little 



