96 IM'.CdRliS OF THK AUSTKAI-IAN MLSEfiM. 



The Medusa fiix'tlier agrees in liabit witli tlie Cape species since it 

 Avas never t)bserveil to swim ; neitlier could any swinnning- motion be 

 induced by dropping tlie specimens into sea-water. They would tall 

 straight to the bottom of the vessel and then move along the surface of 

 the glass by slow crawling movements. 



The following observations supplement the published accounts of the 

 liabits. During the examination of the living Metiusse in a shallow glsiss 

 dish on the stage of a microscope tlie specimens over the area of l>right. 

 light admitted through the stage aperture were observed to move off to 

 those parts of the dish which were outside the circle of illumination. 



The influence of background on the movements of the animal was also 

 noted. Several specimens were placed in a dish of which one-half of the 

 bottom was white, the I'emaiuder black. When the disli was so orientated 

 that the two halves were equally illuminated, all tlie Medusae giadually 

 passed to the black half. 



Family CLADONEMID^. 



Genus Cnidunkma, (rih-hn'^f. 



•G 111 do)ie Ilia, Gilchrist, Quart. Joiirn. Micro. Sci. (n.s.), I.xiii., 4-, 1919, 

 p. 525. 



The genus (' uiiUniriiin, with ('. cnjunir'e for its ty])e, was founded by 

 Gilchrist for a species of crawling Medusa from the Cafie of Good Hope 

 possessing the following chaiactei-s : — - 



"Medusa: adapted for crawling or walking ; no brood-jiouch above 

 stomach ; gonads well-developed, in ectodermal inter-radial pockets around 

 stomach; sexes separate; radial canals usually six : tentacles numerous, 

 increasing with age, and not corresponding to number of radial canals, 

 dichotomous ; the upper branch with sevei-a! clusters of nematocysts in 

 addition to a terminal cluster; nooial tentacles; thick nematocyst ring 

 under margin of bell. Hydroid ; with one verticil of tliree capitate 

 tentacles, and a second of six non-capitate tentacles." 



On these generic characters Gilchrist separates the Cape species fi'oni 

 tlie crawling Medusse ( I'Jlei(tlieriti) of the Northeiii Hemisphere. He also 

 maintains as distinct S[>ecies of the genus Citiduiieiun the previously 

 described crawling ^ledusa? from the Southern Hemispheie, and establislies 

 Vanhoften's Kerguelen specimens as a new species, t'lilildiii'iiiu /,-criim'l('iieiise, 

 characterised by having the nematocyst-clusters lateral in |)osition, the 

 radial canals un branched, and the nematocyst ring complete. 



The propriety of i-eferring all the species of ci-awling Medusje from 

 the Southern Hemisjiliete to the genus Cnidtmciiin presents cei'tain 

 dithculties to which Gilchrist has drawn attention. For instance, the 

 hydi'oid form is known only in the case of ('. i-hjh'iisi', while the ectodermal 

 ])ouches in which the gonatis are partly lodgcil in the Cape species have 

 not been recognised in rlie other southein forms i-.xcept, according to 

 Gilchiist, in the case ol the nnilc of ('. I;eriiiieleiieii!<e. (iilchrist, liowever, 

 would seem to have somewhat misinierpri'ted V}inh('>f'l'en"s remaiks on tlie 

 arrangement of the gonads in the Kerguelen species. 



