A FURTHER NOTE ON KERATOSUM COMPLEXUM. 1 89 



Keratosum any tendency toward a bilaterality in the growth 

 habit such as described for Clathrozoon wilsoni. But here again 

 we have a feature which need hardly be considered incompatible 

 in the family aspects of the species. One finds such differences 

 of aspect in genera and species of Gorgonidae, to which Clathro- 

 zoon bears some superficial resemblance. I am constrained to 

 believe that in its family relations Keratosum is more closely 

 akin to Hydroceratinida? than to any existing family of Hydrozoa, 

 and am quite prepared to propose that it be so designated, at 

 least until stronger reasons are found for a different disposition. 



In closing, attention may be called to a still further coincidence 

 between Keratosum and Clathrozoon, namely, the absence in both 

 of any trace of reproductive organs. I had already emphasized 

 this in the original description of Keratosum, stating that while 

 an absence of germ cells might call for no surprise, yet "if 

 gonangia are an organic part of the skeleton one might expect 

 some trace of them, . . . but none could be recognized." 



This further inquisition into the morphology of these hydroids 

 tends to confirm and emphasize what had been said in concluding 

 my original description, that "we have in this hydroid one of 

 the most interesting, and in some ways anomalous, of this re- 

 markable group of organisms." The foregoing comparison of 

 the species with that from Australia, Clathrozoon wilsoni, tends 

 to further accentuate this impression. 



NAPLES ZOOLOGICAL STATION, 

 January 3, 1911. 



