12 i;i>\VAi{i» 'I'. i:i;oWNi:. 



This tliiek luise is appaiTUlly al>.seiit in .1/. iin.yfni/is, Iml as the top nf tiu- uiiilirclla is 

 (•ruslu-il in, it is impossil>lc to sec every detail clearly. 



The arrniijutonient of the tentacles is similar in both species. There are two 

 tentacles, one placcil behind the other (PI. IV., fij,'. 7), on each of the four pcrradial 

 bulbs. Mv figures of ^f. Imrtlaubi .show the tentacles in this po.sition, but I omitted 

 to direct attention to the arrangement of the tentacles in the description of the 

 specie.s. Both species have practically the same kind of basjil bulb. The tentacles 

 of M. au.'<tr(ilis are closely contracted, and it is impossible to make out the arrange- 

 ment of the nematocysts upon the tentacles. This is unfortunate, bccau.se if the 

 structure of tlie tentacles .should differ from Af. hartlatJn, we should have a useful aid 

 towards the determination f)f the species. I have decided to give the Antarctic 

 Marqchips'is a .specific name because I cannot prove that it is identical with 

 JA. Iiiirtiiuhl. One really wants another specimen in far better condition tli.m this 

 to definitely elucidate the .specific characters. 



The Medu.sa; which Prof. Dendy (1902) found attached to the Hydroid Pela- 

 qohydra inirtibilis, which was washed up on the coast of New Zealand, probably 

 belong to the mcdu.soid genus Afargeliqinls. As these Medusa) liail not detached 

 themselves from the Ilydroid and were without gonads, they must be regarded' as 

 <[uite early stages. They have five tentacles on each of the four pcrradial ba.sal 

 bulbs. These tentacles are arranged in two pairs, one behind the other, with the 

 fifth tentacle by itself on the innermost side of the basal bulb. 



Family TIARIDiE. 

 Catablema, Ilaeckel, 1879. 



Generic C//arac/cr. —Tiaridaj with radial canals having lateral branches or 

 diverticula. 



The above definition of tlie genus may be regarded as rather vague, but it can 

 be ad<led to when all the genera and .species of the Tiarida; have undergone a 

 thorough revision. The conformation of the sexual organs has hitherto been used 

 as the chief means of distinguishing the different genera, but 1 am rather inclined 

 to use the shape of the gonads for one of tiie specific characters. A new Antarctic 

 species compels me either to omit the gonads from the generic character or to 

 establisli a new genus. I prefer, at any rate for the present, to place tlie new 

 species in tiie genus Cntiihlema. Tlic new .species is named after the late W. F. It, 

 Weldon, who was for .some years Profe.s.sor of Zoology in University College, and 

 who gave me my first lessons in this fasiinating subject. 



One of the characters which has always been associated with tiie genus C'ataUeiiia 

 is the presence of diverticula on the radial canals ; l)ut other .species with similar 

 diverticula have Iteen placed in the genus Turrit, because the conformation of their 

 gtmads is not like that in the typical ('uliihli'iiiu. The type species of the genus Tunis 



