rare Plumularian Ilydroid. 313 



a move globular, less deep lijdrotheca, with fewer and more 

 definite marginal sinuations, in possessing two, seldom three, 

 internodal ridges, and in having the nematophore septum 

 much nearer the base of the hydrotheca. The serrations on 

 the margins of the nematophores, noticed by Billard "^j are 

 less distinct than in C. formosus, although, as there, the 

 mesial nematophore on the proximal internode of each hydro- 

 clade lies below the hydrotheca and is free from it. The 

 presence of this nematophore, the existence of which Allman 

 denies, shows that the pliylactogonium cannot be " its 

 morphological representative." On the hydroclade-beaving 

 tube five nematophores usually accompany each hydroclade : 

 one posterior, in the angle between internode-process and 

 internode ; one anterior, distal to the process, and three, 

 almost in a whorl, proximal to it. 



The ' Challenger ' specimen I regard as a variety of 

 Cladocarpus crenatus (Fewkes) described by Fewkes, in 

 absence of the gonosome, as Aglaophenia crenata f. Clado- 

 carpus crenatus, var. allmani, nov. nom., differs from the 

 type of the species in possessing only two instead of eight 

 internodal ridges and in having three anterior teeth much 

 more prominent than the lateral sinuations. The free portion 

 of the mesial nematophore, too, is scoop-shaped, open towards 

 the hydrotheca ; but while Nutting describes that of C. crena- 

 tus as " tubular" |, one of his figures (pi. xxiii. fig. 9, upper- 

 most hydrotheca) represents it as open on the side facing 

 inwards. This variety was obtained by the ' Challenger' in 

 lat. 34° 5^' N., long."l39° 30' E., in the neighbourhood of 

 Yokohama. 



The following measuiements indicate, in mm., the sizes of 

 the species discussed above : — 



C. formosus. C. crenatus, 

 Tar. allmani. 



Stem internode?, length 0-91-0-98 Not discernible. 



Hydroclade internode?, length . . 0'84 077 



Hydrotheca, depth 0-57 0-42-0-45 



,, diameter at mouth . . 0-35 0"32 



Gonotbeca, length 1-23 1-08 



„ greatest diameter .... 0-70 0-59 



* Billard, A., 1908, " Sur les Plumulariidse de la collection du 

 ' Challenger,' '' Comptes Reudus de I'Acad. des Sc, 16th Nov., 1908, 

 p. 3. 



t Fewkes, J. W., 1881, " Report of the Acalephse, Hydroida, ' Blake ' 

 Expedition," Bull. Mus. Comp. Zuol. Harvard, vol. viii. no. 7, p. 132. 



\ Nutting, C. C, op. cit. p.' 104. 



