CONTRIBUTIONS TO THE ANATOMY OF THE BRACHIOPODA 327 



to break away the end of the intestine of Lingula from its attach- 

 ments without considerable violence. 



Thirdly. If the extremity of the intestine, either in Rhynchonella 

 or in Waldheimia, be cut off and transferred to a glass plate, it may 

 readily be examined microscopically with high powers, and it is then 

 easily observable that its fibrous investment is a completely shut 

 sac. In Rhynchonella the enlarged caecum is often full of diatoma- 



Fig. I. Rhynchonella fsittacea, viewed in profile ; the lobes of the mantle and the pedicle 

 being omitted. 



a. mouth ; b. oesophagus ; c. stomach and liver ; d. intestine ; e. imperforate rectum ; 

 /. mesentery ; g. gastro-parietal bands ; h. ilio-parietal bands ; i. superior ' heart ' ; 

 k. inferior ' heart ' ; /. genital bands ; in. openings of pallial sinuses ; n. pyriform vesicle ; 

 u. sac at the base of the arm ; p, ganglion ; q. adductors. 



ceous shells, but it is impossible to force them out at its end, while if 

 any aperture existed they would of course be readily so extruded. 



However anomalous, physiologically, then, this cxcal termination 

 of the intestine in a molluscous genus may be, I see no way of 

 escaping from the conclusion that in the TerebratulidcE (at any rate 

 in these two species) it really obtains. There are other peculiarities 



