252 sujniAUY of current researches relating to 



fastening itsulf, the planula elongates and forms a layer of pcrisarc, 

 by means of which it is fastened throughout its entire length. It 

 does not become a hydranth, but a hydrorhiza ; the first hydranth is 

 formed as a buil, which grows out at right angles to the long axis at 

 the end opposite the adhering gland. 



The formation of the first hydranth from the planula is therefore, 

 in this species at least, a process of metagenesis rather than a meta- 

 mori^hosis, and this is also the case in Hi/dractinia, where the planula 

 becomes a root, and produces the first hydranth by budding. 



The young hydranth of Eutima has a tentacular web, and the 

 tentacles are situated in definite radii, cp. Podocoryne iKBchelii. There 

 are five equidistant large tentacles which are the first to appear, and 

 alternating with these five smaller and younger secondary or inter- 

 radial tentacles. 



Tetraplatia volitans.* — C. Viguier has a note on this rare Coelen- 

 tcrato, which has recently been abundant in the Bay of Algiers; 

 after a reference to the work of his predecessors — especially Krohn 

 and Claus — he discusses the nature of tho so-called otolith, which 

 has been the chief cause of the animal being placed with the Medus83. 

 As a matter of fact, the organ is not prismatic in form, but more 

 like a mushroom with a short stalk. There is a central chamber, 

 which is almost entirely filled by the pedicel ; with Claus, the author 

 failed to detect any nerve-fibres passing to the organ. Further, with 

 true otoliths, the addition of acetic acid results in the disappearance 

 of the calcareous body, but here the refractive body takes on a brown 

 colour, like the cells that surround it, and retains both its form and 

 size. Lastly, Viguier has been able to note that the body may spon- 

 taneously become phosphorescent, and be of a blue colour ; he explains 

 the fact that this phenomenon has not been previously noticed by 

 saying that, though he has kept a number of specimens, he only once 

 observed it ; but on that occasion it was very well marked. 



Australian Hydromedusae.f — E. v. Lcndenfeld describes (Parts 

 1-3) a series of new species of Australian Hydromedusn3, and proposes 

 a new classification, dividing the Hydromedusfe into four sub-orders 

 and eighteen families. The most interesting of the new forms is Eu- 

 denclrinm generalis, the male polypostyls of which show a great simi- 

 larity to Medusa). They possess four aboral tentacles in the principal 

 radii, and on these the spermatozoa reach maturity. These tentacular 

 appendages arc therefore homologous to the radial canals of the 

 Craspedote Medusa). Diphosia symmetrica nov. sp. produces perfectly 

 bilateral symmetrical female gonangia. 



In the 4th part the numerous Australian species of Graptolithidaa, 

 Plumularidai, and Dicorynidae are catalogued, and a large number of 

 new species and one new genus (Pentandra) discovered by the author 

 are described and figured. The Australian Plumularida3 exceed in 

 number of species those of all the rest of the world put together. 



• Comptes Eendus, c. (1885) pp. 388-90. 



t Proc. Linn. Soc. N. S. Wales, ix. (1884) pp. 206-41, 345-53 (1 pi.), 401-20 

 (2 pis.), 467-92 (6 pis.), 581-634 (10 pla.). 



