364 ON THE ANATOMY 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 presence 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 oi Physophoridce, by means 

 of which he believes it to be satisfactorily demonstrated that there 

 exists a unity of organization between the two families of Diphyidce 

 and Physophorid(£ ; 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 : i. body composed of two 

 membranes, out of which the organs are modelled ; 2. thread-cells 

 universally (?) present ; 3. gemmiparous generation ; 4. sexual 

 generation, spermatozoa and ova being formed in vase-like external 

 sacs. 



The paper was accompanied with a series of illustrative drawings. 



