DESCRIPTION OF SPECIES 81 



Zoom (Text-fig. 22). The zooids agree closely with Michaelsen's (1924) detailed description, 



except that the stomach (st.) of the ' Discovery ' specimens has rather more folds, there being up to 



twenty instead of fifteen as noted by Michaelsen. 



Gonads. Many of the zooids in the ' Discovery ' colony have no trace of gonads, but in a few there 



is a large testis (t.), consisting of many closely packed small orange-coloured follicles forming a long 



body situated entirely behind the loop of the intestine. The sperm duct (s.d.) is sinuous or hooked at 



Text-fig. 22. Hypsistozoa fasmeriana (Michaelsen) (St. 935): Zooid. 



its origin. No female gonads were seen, although, as Brewin (1946) has shown, the zooids are herm- 

 aphrodite. There were also no brood pouches. 



Remarks. The species was very carefully described by Michaelsen (1924) who, in the absence of 

 gonads in his specimens, put it in the genus Distaplia. But Brewin (1946) found specimens with 

 gonads which projected into the right anterior part of the vascular process, and she later erected a 

 new genus Hypsistozoa for the species (Brewin, 1953). 



The annual cycle and the complex and interesting embryonic development have been described in 

 detail by Brewin (1956a). 



