HYDROZOA — RITCHIE. 863 



is strictly terminal, the remainder lying on the exterior ridge of 

 the sarcotheca, and being directed backwards. 



A similar development occurs in the median sarcotheca, which 

 is short and stout, projecting outwards and upwards parallel to 

 the hydrotheca wall, from which it is altogether free. In its 

 simplest form, it possesses two openings, one terminal, the other 

 at its base facing towards the hydrotheca. But the terminal 

 opening may become slit-like, and, by tlie median closing of the 

 slit, two apertures may be formed. These, developing become 

 -quite distinct, and the median sarcotheca appears to be bifurcated 

 (PI. Ixxxix. figs. 8, 9, 10, 11). The abcauline wall of the hydro- 

 theca is continued half-way across the base of the mesial sarco- 

 theca as an S-shaped process The cauline sarcothecse have 

 ah-eady been described. Goyiosome. — Unknown. 



Dimensions. — 



Stem, cladate tube, diameter 0'087-0099 mm. 



Hydroclade, internode, length 0-73-0'78 ,, 



Hydrotheca, depth 0-52-0-57 ,, 



,, diameter at "waist," side view 0-14 ,, 



,, diameter at mouth, side view 0-21 ,, 



,, diameter at "waist," front view 0'10-0"11 ., 



,, diameter at mouth, front view ... 0*21 ,, 



Affinities. — Owing to the absence of the gonosome, I am unable 

 to give this species its definite generic rank. Its relationships 

 are, however, apparently with those elongated, multiseptate 

 species of Cladocurpus and Aylaophenopsis which have hitherto 

 been found only in American waters. It approaches Cladocurpus 

 tenuis, Clarke,^" differing at least in the structure of its sarco- 

 thecae, the robustness and proximity of its hydrothecse, in the 

 more definite arrangement of the internodal septa, in the absence 

 of nodes in the stem, and possibly in having its stem fascicled. 

 There seems to me also to be a close relationship between this 

 species and Cladocarpus disiovius, Clarke, from tlie Eastern 

 Pacific, near Panama, in spite of the fact that no internodal 

 septa occur in the latter and that an additional nematophore is 

 present on each internode. 



It is interesting to note that Pluinularians of this elongated 

 type have hitherto been found only in American waters. 



Locality. — Station 57, off Wata Mooli, three and a half to four 

 miles from shore ; depth, 59 to 54 fathoms; bottom, mud ; 22nd 

 March, 1898. 



Type Specimens. — In the Australian Museum, Sydney. 



s^ S. F. Clarke — Reports on the Dredging Operations of the " Blake" — 

 Hydroida: Bull. Mus. Comp. Zool. Harvard, v., p. 247, pi. v., figs. 31, 316, 



