TRANSACTIONS OF THE SECTIONS. 95 



near the centre, with one extremity expanded and opening into the visceral chamber, 

 the other tapering and opening externally. These organs are placed one on each 

 side of the intestine, and the apertures by which they communicate with the pallial 

 chamber are situated near the junction of the two pallial lobes, one on either side of 

 the mouth. 



In JRhynchonella there are four of these organs, as first pointed out by Mr. Huxley, 

 all of which open externally. Two correspond in situation with those of the Tere- 

 bratulidx, the other two being placed at the sides of the liver a little above the for- 

 mer. Lingula is supplied with a pair of these so-called hearts, which do not-difFer 

 materially from those already described. 



The external apertures of these organs I have seen in every instance, and though 

 I have searched with the greatest care, have entirely failed to detect any arteries or 

 vessels, or anything that could be taken for such, passing from their apices to the 

 ovaries, or to any other part. When I first detected the external apertures I thought 

 they might possibly be ruptures of the tissue ; but further experience prohibits any 

 such notion. They are always placed symmetrically, and are of equal size, resem- 

 bling each other in form, and in every respect are similar, which would not be the 

 case were they formed accidentally. 



It is quite evident that these organs are not muscular centres ; some other func- 

 tion than that of propelling blood must be assigned to them. I was originally dis- 

 posed to look upon them as oviducts, and such I still believe them to be. It has, 

 however, been suggested to me by Mr. Huxley that they are possibly renal organs, 

 and that they may perhaps serve also as oviducts. This appears plausible enough, 

 and may probably turn out to be correct. Professor Owen supposes that the eggs 

 escape by dehiscence of the pallial membrane. Such a theory might seem feasible 

 in respect to those Brachiopods v^hich have the ovaries situated between the layers 

 of that organ ; but in Lingula they are developed in the visceral chamber attached 

 to membranes to which the pseudo-hearts are appended. Here then the ovaries 

 and these peculiar organs are brought into intimate relationship with each other ; 

 and it would appear more likely that the eggs should escape by this conduit than 

 that they should have to find their way into the pallial sinuses and then escape by 

 the rupture of the membranes. The walls of the conduit are of a glandular nature, 

 and the lips of the internal aperture are spread out like the mouth of a funnel, as if 

 for the very purpose of receiving the ova on their escape from the ovaries. 



The alimentary tube in the TerebratulidcB and Rhynchondlidce \Bvemz,rV&h\&{ovt\ie 

 firmness of its walls, which never collapse, though the oesophagus is generally a little 

 compressed. It is bent into the form of a siphon, the arch being turned towards 

 the dorsal or imperforate valve : the oesophagus represents the short, the stomach 

 and intestine the long arm. The gastric organ, though small, is distinctly marked ; 

 it is irregularly oval, and suddenly contracting posteriorly gives origin to the intes- 

 tine, which is short, and is suspended by a membrane in the midst of the visceral 

 chamber. This portion of the alimentary tube passes downwards and terminates 

 behind the adductor muscle, having a cardinal muscle on each side. In the Tere- 

 braiulidcB it gradually tapers towards its extremity, which is rounded and imperforate. 

 In Waldheimia Australis it abuts against the membrane circumscribing the visceral 

 chamber, to which it is firmly attached. But in Waldheimia cranium and Terebra- 

 iulina caput-serpeniis there is no such attachment, the rounded cmcal extremity ter- 

 minating at some little distance from the neutral wall of the chamber. The intestine 

 of Rhynchonella on reaching this point doubles upon itself, and then advancing a little 

 ends in an enlarged rounded extremity, which inclines to the right, and projects freely 

 into the centre of the visceral chamber. In this, as in the Terebratulida?, there is no 

 anal outlet, the termination of the intestinal tube being csscal. This is perfectly 

 obvious in Rhynchonella psittacea. I have nevertheless made every endeavour to find 

 an anal perforation ; I have made numerous dissections under apoweiful doublet, — 

 have removed the part and examined it with the microscope ; I have filled the tube 

 with fluid as the finger of a glove with air, and by pressure have attempted to force 

 a passage ; I have tried injections ; but have equally, on all occasions, failed to 

 discover an outlet ; and have only succeeded in demonstrating more and more clearly 

 the ceecal nature of the terminal extremity of the alimentary tube. Therefore, how- 

 ever it may be opposed to analogy, the fact must be recorded, — there is no anal 

 orifice in Waldheimia, Terebratulina and Rhynchonella. 



