HALOCORDTLE COOFERI. 79 



The male gonophore is adelocodoiiic, there being* no open- 

 ing- to the nmbrella cavity. 



The male gonophore is characterised by the presence of 

 fovir little papillee of ectoderm projecting into the umbrella 

 cavity (text-figures 1 and 2, p). They arise opposite the 

 fourth radial canals (fig. 4) toAvards the upper end of the 

 gonophore. It may be noticed that the fiat layer of ectoderm 

 lining the umbrella cavity thins oif and apparently disappears 

 around the base of the mushroom-shaped papilla. It is not 

 possible, at present, to suggest any function or meaning to 

 these very curious structures. They consist of elongated 

 ectoderm cells with fairly conspicuous nuclei. They have 

 not been found in the female gonophore, but they occur in 

 all the mature male gonophores that have been examined. 

 I am not aware that similar structures have been recorded in 

 other gono])hores or medusa?. Their position on the radial 

 canals recalls the gonads of calyptoblastic medusie. 



The male gonophore dehisces by the expansion of the 

 endodermal spadix, which forces its way through the distal 

 extremity of the gonophore (fig. 2). 



(4) Systematic position. — The present species differs 

 from P. cavolinii Ehren, and P. gibbosa^grasv*?, and agrees 

 with Halocordyle tiarella [Ayres], from the Atlantic 

 shores of North America, in that the capitate tentacles tend 

 to be arranged in whorls instead of being ii-regularly scattered. 

 It is very interesting, however, to note that this verticillate 

 character seems to be on the point of being acquired. In 

 several colonies collected, which appear to dift'er in no other 

 character, I have found great irregularity in the disposition 

 of the capitate tentacles. In these colonies some of the 

 polyps may have a distinct distal verticil of four capitate ten- 

 tacles, while below these there are scattered seven or eight 

 capitate tentacles with no obvious arrangement. In a very 

 few of the polyps some twelve capitate tentacles are irregu- 

 larly scattered, and even the distal verticil is indistinguishable. 

 It is important to notice that this tendency to vary in the 

 arrangement of the tentacles concerns the colony as a whole. 



