SUPPLEMENTARY APPENDIX. 27 



of the 'heart' in this genus was explained, and the plaited auricle discriminated from the ventricle in 

 Waldheimia Jlavescens." Mr. Huxley observes two of these "hearts" situated as described by Professor 

 Owen, but in Bhynckonella psittacea he found four : the auricles of this last being smaller, both actually and 

 proportionally than in Waldheimia. " Two of these occupy the same position as in Waldheimia close to the 

 origins of the calcareous crus : while the other two are placed above these and above the mouth, one on 

 each side of the liver." 



After entering into minute details regarding the mesenteric and other bands which support the alimentary 

 canal 1 and "hearts," Mr. Huxley concludes that "the facts then with regard to the real or supposed circu- 

 latory organs of the Terebrahdidce are simply these : 



" 1 . There are two or four {hearts), composed each of a free funnel-shaped portion with plaited walls, 

 opening widely into the visceral cavity at one end, and at the other connected by a constricted neck, with 

 narrower, oval or bent, flattened cavities, engaged in the substance of the parietes. The existence of 

 muscular fibres in either of these is very doubtful, it is certain that no arteries are derived from the apex of 

 the so-called ventricle; but, whether this naturally opens externally or not is a point yet to be decided. 2 



" 2. There is a system of ramified peripheral vessels. 3 



"3. There are one or more pyriform vesicles. 



"4. There are the large sinuses of the mantle, and the visceral cavity into which they open." 



To determine in what way these parts are connected, and what functions should be ascribed to each : it 

 appears to Mr. Huxley, and indeed to us all, that much further research is required ; and it is to be hoped 

 that some one provided with an ample supply of specimens may take up the subject, for it is only by such 

 aid, that the difficult problems involved in this investigation can be settled. 



Mr. Huxley concludes his valuable memoir by stating, "All we have seen of the structure of these 

 animals leads me to appreciate more and more highly the value of Mr. Hancock's suggestion, that the 

 affinity of the Brachiopoda are with the Polyzoa. As in the Polyzoa the flexure of the intestine is neural, 4 

 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, one 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 appear wide enough, yet the Avicularium of a Polyzoon is exceedingly close and 

 striking." 5 



1 The Mesenteric band is particularly interesting in relation to the dorsal septum of Pentamerus and the 

 " Shoe lifter," process of Camarophoria. 



2 Mr. Hancock and Mr. Huxley deny the arterial origin of the centre lines observed in the vascular 

 impressions of Camarophoria by (King), and Terebratella by (Owen.) 



3 It is a portion of this system which appears to have been described as a muscular structure for 

 injecting and extending the arms. 



I may also here remark that Mr. Hancock appears to believe that the so-called Cuvierian hearts will 

 prove not to be " hearts." He also informs me that the peripheral net-work or sinuses undoubtedly exist, 

 and that he has frequently seen them both in the mantle, arms, and elsewhere. 



4 The term "neural" is applied by Mr. Huxley to the ventral side of invertebrate animals; in the 

 vertebrata the dorsal side is "neural." 



5 Mr. Huxley's examination of the ovarian sinuses of Bhynchonella psittacea is quite confirmatory of 

 the interpretation given by Mr. Woodward and myself of the remarkable spaces in the Ortiiid.e and 

 Rhynchonellid.®, and of the distinction (founded on them) between these families and the 

 Terebratulid^e. 



