286 



Royal Society. 



adductor muscle. M. Gratiolet, in a late communication to the 

 Academie des Sciences, takes the same view. To get rid of the ob- 

 vious difficulty, that this spot is covered by the shell, and therefore 

 that if the anus existed here, there would be no road of escape for 

 the faeces, Mr. Hancock and Mr. Woodward appear to be inclined 

 to suppose that some cloacal aperture must exist in the neighbour- 

 hood of the pedicle. 



The existence of any such aperture, however, has recently been 

 denied with great justice by Professor Owen. 



The result of my own repeated examinations of Rhynchonella psit- 

 tacea and of Waldheimia flavescens is — 1. that the intestine does not 



Fig. 1. 



Fig. 1. Rhynchonella psitlacea, viewed in profile; the lobes of the mantle and 

 the pedicle being omitted. 



Fig. 2. The same viewed from behind, the pedicle having been cut away. The 

 left half of the body and the liver are omitted. 



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

 rectum ; f. mesentery ; g. gastro-parietal bands ; h. ilio-parietal bands ; i. superior 

 ' heart ' ; k. inferior ' heart ' ; I. genital bands ; m. openings of pallial sinuses ; 

 n. pyriform vesicle ; o. sac at the base of the arm ; p. ganglion ; q. adductors. 



