A COLLECTION OF HYDHOIDS. 291 



Gonosome. — In the dwarf vai-iety the reproductive bodies 

 have not been met witli, although they have been searched 

 for in what appear to be old colonics, since they extended 

 over considerable areas. 



In the large variety the male reproductive bodies only have 

 been found (text-fig. 4, A). It is clear that they are fixed 

 gonophores, and they do not apparently differ from those 

 described for pusilla. 



Small errant polyclut^ts and chtetognaths appear to form 

 the staple food of this hydroid. 



(11) Sertularella polyzonias (Lin.). (PL XLVII, figs. 



18-20.) 



Sertulakella polyzonias (Lhi.) Syst; Hincks. T.. "A History of 



the British Hydroid Zoophytes," 

 1868. p. 235; Bale,W. M.. 'Cat. 

 of the Australian Hydroid Zoo- 

 phytes/ 1884, p. 104 ; Nutting, 

 C. C, 'American Hydroids.' pt. 

 ii, •' Sertiilaridse," 1904, p. 90. 



It is scarcely possible to define this widely distributed 

 species with any certainty. It is very variable, and the Xatal 

 hydroid is referred to it, as it is undesirable to found new 

 species on characters (such as the presence or absence of 

 internal knobs of chitin at the mouth of the hydrotheca) 

 which are admittedly highly A'ariable. 



The hydroid is found on sea-weeds and worm-tubes, the 

 colony is pale brown, and the stems may reach a height of 

 three quarters of an inch. 



Teophosome. — Hydi-orhizfi has an irregular outline, and 

 branches sparingly. 



Diameter, about 0*242 mm., and thickness of perisarc, 28 /j. 



Hydrocaulus. — The hydrorhiza produces at irregular 

 intervals upright stems bearing from 13-20 hydrotheca?. 

 The stems are generally unbranched, but occasionally a 

 lateral branch may be formed (text-tig. o,A). The stem is 

 divided into faintly-defined internodes by oblique divisions. 



