68 Linnean Society. [Feb. 5, 



animals is overlooked ; by all, except Will, the demonstration of the 

 generative organs is omitted, and even he mentions vpith some doubt 

 the male sac only ; and lastly there is no attempt made by any of 

 them to trace the various organs through their development, or to 

 establish on the ground of anatomy the natural affinities of the 

 group. To these latter points, Mr. Huxley states, that his attention 

 has been chiefly directed during a voyage of some months through 

 the South Atlantic and Indian Oceans, in the course of vphich he has 

 examined several genera both of Diphyidce and Physophoridce, with 

 as much care and attention as the inconveniences of ship-board 

 vs'ould permit. The results are given under the following sectional 

 divisions, viz. : 1. a description of the different species examined ; 

 2. their anatomv ; and 3. a comparison of Diphyida and Physopho- 

 ridce. Under the first head Mr. Huxley describes four species of 

 Diphyes, one of Calpe, one of Eudoxia, one of Aglaisma ?, and one of 

 Rosacea. He then enters at length into the anatomy of the different 

 parts of the body, under the several heads of the common tube ; the 

 natatorial organs and the duct connecting their cavities with the 

 common tube ; the nuclear piece or bract and its sacculus ; and the 

 polypoids, each consisting of a stomachal sac, a prehensile organ and 

 a generative organ. Although generative sacs were found by the 

 author in all the genera examined by him, it was only in Eudoxia 

 and Aglaisma (}) that he procured unequivocal evidence, by the pre- 

 sence of ova, of their real nature. No unequivocal male organs were 

 observed, although the so-called " entozoa " of Will were frequently 

 seen swimming about in the cavity of the young generative organs. 

 But they were not more abundant in these situations than in the 

 stomachal sacs, common tube, &c., and their dissimilarity to true 

 spermatozoa is too great for any conclusions to be founded on their 

 presence. The total absence of male sacs, and the rarity of ova in 

 the females, may, Mr. Huxley thinks, be accounted for by the season 

 during which his investigations were carried on, the months of 

 March, April, May and June being the winter of the Southern 

 Hemisphere. Lastly, the author enters on the comparative anatomy 

 of various species of Physophoridce, by means of which he believes it 

 to be satisfactorily demonstrated that there exists a unity of organi- 

 zation between the two families of Diphyidte and Physophoridce ; and 

 concludes by stating his opinion that at least two other families, the 

 Hydriform and Sertularian Polypes, should be arranged with them in 

 one natural group. The structural coincidences in these families he 

 enumerates as follows : 1 . body composed of two membranes, out of 

 which the organs are modeled; 2. thread-cells universally (?) pre- 



