A COLLECTION OF HYDROIDS. 



313 



rliiza readily distinguishable from the hydrorhizte of other 

 hydroids amongst which it may be living. 



Diameter, from above, 0-121 mm. ; thickness of perisarc 9 /n. 



Hy drocaulus. — Consists of upright stems with no internal 

 pegs. Divided by oblique nodes into regular internodes, 

 bearing a pair of hydrothecfe, or two or three pairs in a 

 closely compressed group. 



Diameter of base of stem 0-081 mm., thickness of perisarc 

 15 fi, length of internode 0-798 mm. 



Hydrotheca. — On the first internode there may be only a 

 single opposite pair, in contact for about ^-h their height in 



Text-fig. 11. 





Pasythea qiiadridentata {Ellis and Sol), x 30. 



front, the distal part curving to a narrow tridentate mouth 

 looking outwards. Two lateral teeth (fig. 11, 2,2), one adcau- 

 line (i). Operculum of two flaps. Length of proximal 

 hydrotheca, measured parallel to abcauline edge, 0-283 mm., 

 greatest breadth 0-145 mm., thickness of perisarc 10//. 



H y d r a n t h . — 1 8-15 tentacles. 



Gonosome. — Female gonangium borne at the base of the 

 stem ; ovate, with 5-6 transverse rugaj. Very broad aperture 

 with flat operculum (text-fig. 11, ? ), 



Length 0-808 mm., greatest breadth 0-412 mm. 



The above description is practically the same as that given 

 by Nutting. It is stated that "this species seems to be 

 always found growing on floating sea-weed"; but the Natal 



