Royal Society. 



287 



terminate on the right side of the mantle as Professor Owen describes 

 it, but in the middle line, as Mr. Hancock describes it in Waldheimia, 

 while in Rhynchonella it inclines, after curving upwards, to the left 

 side; and 2. that there is no anus at all, the intestine terminating 

 in a rounded caecal extremity, which is straight and conical in Wald- 

 heimia, curved to the left side and enlarged in Rhynchonella. 



I confess that this result, so exceptional in its character, caused 

 me no small surprise, and I have taken very great pains to satisfy 

 myself of the accuracy of my conclusion ; but notwithstanding the 

 strong prejudice to the contrary, to which the known relations of the 

 anal aperture in Lingula gave rise, repeated observation has inva- 

 riably confirmed it. 



Professor Owen's statement is, that in Rhynchonella (Terebratula) 

 psittacea " the intestine inclines to the right side and makes a slight 

 bend forwards before perforating the circumscribing membrane in 

 order to terminate between the mantle lobes on that side." — On the 

 Anatomy of the Brachiopoda, p. 152. 



1 find, on the contrary (figs. 1 and 2), that the intestine passes 



Fig. 2. 



at first straight downwards in the middle line, as in Waldheimia, but 

 instead of terminating in a rounded tapering extremity as in that 

 genus, it bends upwards and then curves round to the left side. 



