Mr. J. D. Macdonald on Phyllirrhoe bucepbala. 141 



nen'ous matter break up like a dividing vessel, without preserving 

 the individuality of distinct nerve-tubes. 



The sexes are combined in Phyllirrhot; the male and female 

 generative openings lying close together on the right side of the 

 body in the inferior gastero-hepatic space, and before the anal aper- 

 ture. The ovaries lie in the inferior recto-hepatic space, varying in 

 number from two to live, in general. They are dark-coloured, sub- 

 rotund, and finely lobulated bodies, from the fore part of each of 

 which a very delicate duct arises, and all the ducts unite to form a 

 single tube, with a trifling increase in its diameter. This common 

 oviduct, lined by a pavement of transparent epithelial cells, passes for- 

 wards beneath the stomach in a flexuous manner ; and in the inferior 

 gastero-hepatic space, it first unites with the duct of the testis and 

 again continues its devious course until it ends in the fundus of a 

 much larger tube, whose lining membrane is armed with numerous 

 conical and tooth-like processes, and to this is appended a long ca?cal 

 process much resembling the spermatheca of Helix for example. 

 The external orifice of the male generative apparatus lies immedi- 

 ately posterior to that of the female organs. The testis is rather 

 small, subglobular in form, and closely connected with a short 

 twisted tube*, much dilated at the middle part, and coated over with 

 a layer of dark pigment-cells. It is with this tube, as above noticed, 

 the small oviduct communicates, in order, as it would seem, to permit 

 of self-impregnation, or to answer some other purpose, with the na- 

 ture of which we are unacquainted ; but there is also an intromit- 

 tent organ, which, however, I have never seen ])roperly exserted. 



As to the affinities of Phyllirrhoe with Gasteropods, it may be ob- 

 served that the animal is bisexual, that the eyes, like those of Glaucus 

 and lanthina, are very small and rudimentary, being closely applied to 

 the ganglia of the brain, after the manner of the acoustic sacs, and 

 that both Phyllirrhu'e and Glaucus agree in possessing two lateral 

 horny jaws, articulated with each other superiorly, and bordered 

 with minute conical teeth. 



In the GlaucidcE, the branchiae, which consist of simple papillary 

 projections of the skin, are distributed in an equable manner over 

 the dorsal region of the body ; and any deviation from this arrange- 

 ment would naturally tend, either to a more definite localization, or 

 still further dispersion. It is the latter modification which appears 

 to have taken place in Phyllirrhoe ; so that its respiratory vessels 

 ramify minutely through the common integument, just as the vas- 

 cular trunks analogous to those which break up in the pectinate gill, 

 adapted for aquatic breathing, are subdivided, and spread themselves 

 over the smooth walls of the lung-chamber in Pulmonifera. 



As respects its affinity to the Fteropods, here too the lateral jaws 

 oi Phyllirrhoe xnusthe. borne in mind, together with the almost com- 

 plete suppression of the organs of vision. It is worthy of note also, 

 that its acoustic capsules contain otokonia, as in Pteropoda, instead 

 of single globular otolithes like those of Glaucus, and there is some 



* I have distinctly traced the homologuc of tliis tube in Pteropoda, Ileteropoda, 

 aud the Ganterojioda proper. 



