LIVING BRACHIOPODA. 369 



Bloomfield in Liimbricus arise in close proximity to the nephrostomes. Beddard ('89) 

 also shows that in Acanthodrilus annecteus, the testes are in close proximity to the inner 

 mouths ot" the nephridia. From these descriptions I am led to believe that it is among 

 the chaetopod worms we are to look for structures similar to what has just been 

 described in Terebratulina. 



Accessory Hearts. 



These curious organs have already been fully described by authors and have been 

 briefly alluded to here in connection with associated parts. It is left for me only to 

 describe their appearance in life. We have found that they really occur on separate 

 strands which are not aligned with the ilio-parietal band. I expressed the conviction ('73b) 

 that these organs did not be.ar Hancock's interpretation, and that they properly belong to 

 the genital system and not, as stated by him, to the circulatory system. Subsequent studies 

 of these parts in Terebratulina and Terel)ratalia have only strengthened me in this con- 

 viction ; yet precisely what part they play in this role I am at a, loss to say. The form 

 and size of this vesicle vary more or less in every individual, as may be judged by an 

 examination of plate 59, which is devoted to a representation of its appearance in T. sej)- 

 tentrioiudis and 7'. coremiica. Whether the animal be charged with ova or spermatozoa, 

 the vesicle is always present. Sometimes there are two or more of these vesicles in close 

 proximity, and this duplicature has been noted by Hancock. It would seem that if this 

 organ functioned as a heart, there ought to be some constancy about it in form and size. 

 In some individuals the vesicle has a long peduncular attachment and is testicvdar in 

 shape (59: 4,7). In a careful study of a number of these vesicles, there was found no 

 cavity within, and in no case was there seen any vascular connection witli the genital 

 band from which it sprang. Tlie mass appeai-ed to be glandular throughout and was 

 distinctly tinged with a reddish-yellow, like the nephridiiun. In a niunber, the surface 

 was covered with globular, transparent cells tipped with minute yellow granules appar- 

 ently identical with the knobs already desci'ibed as tipping the filiform spermaries which, 

 we saw, arose from the vesicle, or from its immediate vicinity and also identical with the 

 reddish-yellow cells marking the sperm.aries in the pallial lacunae. In some, a secondary 

 vesicle was found (59: Sre), and in otliers incipient vesicles were budding in close prox- 

 imity (59: 1). A number of my drawings show externally a granidar surface and 

 a structure within, that in one case seemed to be a round, distinct cavity with light 

 reddish-yellow walls. In another instance, I observed what appeared to be an elongated 

 cavity which made nearly a complete turn within the vesicle, one extremity being larger 

 than the other (59: 2). In another case a varicose mass ran over the surface of the 



