BY T. HARVEY JOHNSTON AND O. \V. TIEGS. 220 



whole of this region of the male is wedged into the end of the 

 androecium in such a way that there appears to be a very intimate 

 relationship between the two, amounting practical^ 7 to a fusion. 

 The epithelial cells lining the androecium are squames of about 

 one-half the thickness of those lining the male bodv. These 

 squames at the line of junction of the male and its tube become 

 reflected over the male for a little distance, so that in section 

 one sees a layer of cells of female origin, i.e., those from the wall 

 of the androecium, actually lying outside of, and closely adjacent 

 to, the epithelium of the male. This is well shown in the oblique 

 section figured on Plate xi., fig.23, where one part of the male is 

 seen to be imbedded in the dermis of the androecium, while the 

 remainder is enveloped by the epithelium of the latter, enclosing 

 a part of the cavity of the male tube. Short finger-like pro- 

 longations of this cavity are also seen in section. 



Here, then, is a most remarkable association between the sexes. 

 Not only is the male a parasite as it is in Bonellia, but it lives 

 in a special compartment lying between the two uteri. In 

 Bonellia it is, moreover, a freely motile organism, while in 

 Paeudobonellia the posterior half of the male becomes actually 

 surrounded by female tissues so that the parasitism is of a 

 very much more pronounced type. The whole of the male 

 apparatus is lodged in the coelome of the tiny, spherical, anterior 

 quarter of the animal. This part is connected with the attached 

 region by a zone whose ccelome is very narrow. The posterior 

 region reminds us of a placenta by means of which, no doubt, 

 the male is nourished by the female. Associated with this ap- 

 parently sessile existence, there is a very poorly developed mus- 

 culature, and the alimentary system is almost obliterated, while 

 the nervous system is extremely rudimentary. 



If our interpretation be correct (and it is based on a study of 

 a number of males, both mature and immature, in whole mounts 

 as well as in transverse and longitudinal sections), then the male 

 of Pseudobonellia is an extraordinarily degenerate organism. 

 How it performs its sexual functions is not known. Perhaps 

 the sperms may be liberated into the cavity of the androecium 

 whence they reach the exterior through its canal and enter either 



