SUPPLEMENTARY ADDITIONS TO THE APPENDIX. 



INTRODUCTION. 



The recent dissections of certain Brachiopoda published by Mr. Huxley, in the ' Proceedings of the Royal 

 Society,' for June 1854, [ have cast much light on certain points hitherto insufficiently explained; I will 

 therefore, with the author's kind permission, make a few extracts from some of the most important questions 

 there discussed. 



Mr. Huxley's investigations have been principally made upon the animal of Rhynchonella psittacea, 

 Waldheimia flavescens, and Lingula anatina, and chiefly relate to the alimentary canal and circulatory 

 systems of those genera. 



Mr. Huxley observes that Professser Owen has stated that the intestine terminates on the right side 

 between the lobes of the mantle ; that, on the other hand, Mr. Hancock has declared himself unable to 

 observe at this point any such anal aperture, and concludes from his own observations that the latter is 

 situated on the ventral surface of the animal, in the middle line just behind the insertion of the great 

 adductor muscle. (The termination of the alimentary canal in this position was observed by Mr. S. P. 

 Woodward and myself, in Terebratula vitrea, Terebratulina caput-serpentis, Waldheimia Jlavescens, 

 Kraussia Lamarckiana, and Rhynchonella nigricans ; see 'Cat. Brach. in the British Museum,' p. 48, f. 5, 

 1853, &c. ;) 2 Mr. Gratiolet 3 has also taken the same view, but as the spot thus mentioned is covered by the 

 shell, and that there would be no road for the escape of the fseces if the anus existed there, Mr. Hancock and 

 Mr. Woodward appeared inclined to suppose that some cloacal aperture must exist in the neighbourhood of 

 the pedicle ; 4 Mr. Huxley continues to observe that his " repeated examinations of R. psittacea and 

 Waldheimia flavescens is firstly, that the intestine does not terminate on the right side of the mantle as 

 Professor Owen describes it (in Terebratella) but in the middle line, as Mr. Hancock represents it in 

 Waldheimia,' while in Rhynchonella it inclines after curving upwards to the left side ; and secondly that 

 there is no anus at all, the intestine terminating in a rounded csecal extremity, which is straight and conical 

 in Waldheimia, curved to the left side and enlarged in Rhynchonella (psittacea). This strangely contrasting 

 with the known relations of the anal aperture in Lingula. 



1 Published also in the 'Annals and Mag. of Nat. Hist.,' vol. xiv, 2d ser., p. 285, Oct. 1854. 



2 " The intestine is seen projecting above the oral aperture and fringe. The oesophagus passes through 

 the annular part of the loop." 1853. 



3 ' Comptes rendus de l'Academie des Sciences.' (Paris.) 



4 'Cat. Brachiopoda,' in the British Museum, p. 14, 1853. Mr. Hancock informs me "that he quite 

 agrees with Mr. Huxley, regarding the csecal nature of the intestine, inasmuch as he could not suceeed in 

 finding an anal outlet." 



5 Introduction, p. 55, f. 1. 



4 



