98 SUMMARY OF CURRENT RESEARCHES RELATING TO 



developed tentacles, about 17 rudiments of tentacles, 20 radial and centri- 

 petal canals, 9 completely developed and 7 rudimentary stomachs. Obser- 

 vations were made on the mode and order of development of the gonads ; 

 even the sexual forms may divide by fission. 



The peculiarities of this remarkable form may be thus summed up : — 

 1. Existence of several gastric tubes. 2. Absence of a central stomach. 

 3. The budding, in obedience to quite definite laws, of new tentacles, 

 marginal vesicles, radial canals, gastric tubes, and gonads on the radial 

 canal. 4. Successive and regular right-angled divisions. 5. Variations in 

 the age and size of homologous organs, and the comj^lete absence of a 

 radiate structure. 6. Adradial position of the tentacles, and interradial 

 position of the marginal vesicles. 



In conclusion, the author offers some speculations on the mode of origin 

 of this form, into the details of which we have not space to follow him. 

 If the Medusa had radiate larvfe like Eiicope, which reproduced by suc- 

 cessive rectangular divisions, in the way described by Davidoflf, the series 

 would necessarily give rise to irregular stages ; Dr. Lang thinks that 

 Davidoflfs form was not Phialidium vartabile, but the first stage of Gastro- 

 hlasta. The adult Medusa is the result of continued budding, cotempo- 

 raneous with continiious but incomplete divisions, just as in the animal 

 colonies of certain stone-corals. Many points in the new form call to 

 mind Porpita or Velella among the Siphonophora ; and it is to be re- 

 membered that Prof. Hiickel ascribes a different phyletic origin from the 

 other Siphonophores to the two genera just named. Gastrohlasta timicla 

 from the Red Sea, described by Keller in 1883, has many points of resem- 

 blance to the now species. 



New Sessile Medusa.* — Prof. C. Vogt discovered off the coast of Sar- 

 dinia, at a depth of 50 fathoms, a small organism attached to the stem of a 

 Gorgonia. This he finds to be a medusa, to which he gives the name 

 Lipikea Ittispoliana. 



It has the form of a flat soup-tureen ; the umbrella is drawn out into 

 eight short arms, into which the archenteron is continued; the convex 

 surface of the umbrella is scooped out so as to form a sort of sucker, by 

 which the Medusa remains fixed. The mouth is situated on a short four- 

 sided manubrium, and leads into the archenteron, which is divided by 

 four septa into as many stomachal pouches. There is no marginal canal. 

 There are four pits in the subumbrellar surface, resembling the subgenital 

 pits of the Acrasj^edota, but no genital organs were found ; bundles of 

 gastric filaments are present. The jelly is firm, as in the Craspedota, and 

 only a few fibres (? muscular) are present near the sucker ; but there is a 

 circular band of muscular fibres round the margin of the umbrella. On 

 the subumbrellar surface are numerous glands, containing rounded bodies, 

 like young nematocysts. True nematocysts are present only on the convex 

 surface ; no marginal sense-organs were found. 



Lipkea is, then, a new typo of Hackel's Stauromedusre, differing in 

 certain points both from the Lucernaridse and from Tesseridse. Vogt 

 defines the family as " Stauromedusae with eight hollow arms ; the bell 

 fixed by a sucker ; a continuous circular muscle ; no tentacles, but exhibiting 

 a considerable development of mucous glands." The author considers this 

 new form as supporting his theory that the Medusae are derived from forms 

 primitively free-swimming, but in the development of which are intercalated 

 degenerate, sessile, hydriform persons. 



* Arch. Sci. Phys. et Nat., xvi. (188G) pp. 356-62. 



