330 ERNEST WARREN. 



known locality, and it is only with hesitation that I have 

 sepai'ated them. The chief difference is the presence in the 

 former of a forwardly-directed prolongation of the edge of 

 the internode at the back of the pinna. This, in side view, 

 gives the strongly marked segmented appearance to which 

 the hydroid owes its specific name. Also, in segmentata 

 the median spine at the front margin of the hydrotheca is 

 relatively shorter than in mitrata, and the outline of the 

 margin, although similar, does not appear to be identical in 

 the two hydroids. The colour of mitrata is not stated. 



Without, however, studying a series of specimens, it is not 

 possible to judge with any certainty Avhether these differences 

 are of specific value. 



(28) Aglaophenia chalarocarpa Allman. 



Aglaophenia chalarocarpa Allman. "Description of Australian, 



Cape, and other Hydroida," 'Linn. 

 Soc. Journ. Zool.,' vol. xix, 1885, p. 

 150. 



This is a very common hydroid and has been found in most 

 of the localities that have been searched. It grows in clumps 

 on sea-weeds and sponges, etc., and is of a pale straw colour. 

 It may grow to the height of about one inch, but sometimes 

 shoots with corbulge do not attain a height of more than one- 

 quarter of an inch. 



It appears to agree with the Cape hydroid described by 

 Allman. 



Trophosome . — H y d r o r h i z a, creeping, irregularly branched, 

 sometimes forming a loose reticulum. Diameter about 0'182 

 mm., thickness of perisarc 35 /j. 



Hydrocaulus. — Simple pinnate shoots with stems of 

 variable length. Sometimes the portion bearing the pinna3 is 

 separated from the stalk by a very conspicuous oblique joint. 

 The portion bearing the pinna^ is divided into regular inter- 



