378 bulletin: museum of comparative zoology. 



described by Chun ('98) as palmata is especially confusing because the 

 name was based on the combination of a very early and of a mature 

 stage the connection of which with each other was only a supposition. 

 His young "palmata" is characterized by having peculiar eolid tentilla 

 as well as filiform ones, and in this it agrees with the type species of 

 the genus, H. hormiphora. It further agrees with hormiphora in 

 general form, and in the fact that the adradial canals meet the meri- 

 dionals at about the level of the funnel. The only distinction 

 between this larva, and the adult H. hormiphora, except for differences 

 in development which might be expected, is that the eolid tentilla 

 are proportionately larger, more numerous, and with fewer processes, 

 in the former than in the latter. 



Now, although H. hormiphora is common in the Mediterranean 

 (Gegenbaur, '56, Sars, '57, Chun, '80), and the adult has been well 

 described and figured (as " plumosa") by Chun, and by Mayer (: 12) 

 our only information about its young stages is his figure of a very 

 young larva, so young, in fact (2 mm. long) that filiform tentilla alone 

 have yet appeared; from the stoutness of its ribs, too, it is obviously 

 much younger than his young " palmata." Chun himself has observed 

 that the very youngest "palmata," 3 mm. long, have no eolid tentilla, 

 and that the first tentilla to appear are the filiform ones. 



We need assume merely that the eolid tentilla of the young "pal- 

 mata" become more complex individually, without a corresponding 

 increase either in size or in number beyond the stage which Chun 

 figured, to attain the conditions seen in the adult II. hormiphora. 

 There is certainly no evidence that the eolid tentilla would not undergo 

 further individual development. Indeed the figure (Chun, '88, taf. 

 3, fig. 1) shows that the oldest (terminal) ones have more lateral 

 papillae than the younger ones. And judging from conditions in a 

 group of coelenterates, i. e. the Siphonophores, in which complex 

 tentilla are the rule, not the exception, progressive development of 

 the lateral processes is just what we might expect. 



The developmental series from larval H. hormiphora, through 

 Chun's young "palmata" stages in which the eolid tentilla appear, and 

 become more numerous and complex, to the adult hormiphora reached 

 by progressive development of the individual tentilla as well as of the 

 animal as a whole, is thoroughly in accord with the facts as we know 

 them; there is nothing to forbid the connections here outlined. On 

 the other hand the association of the young "palmata" with the full- 

 grown Hormiphora which Chun ('98) believed to be its adult is sup- 

 ported by no actual evidence. The five large examples had no eolid 



