NECTALIINAE. 289 



Nectaliinae. 



Nectalidae Haeckel, 1888. 



Agalmidae with \'ery much shortened stem, with highly developed ensi- 

 form bracts. 



The only representative of this subfamily is the monotypic genus Nectalia 

 Haeckel, known only from Haeckel's account and figures, and from Chun's 

 ('97b) description of the pneumatophore. According to Haeckel, the bracts, 

 palpons, siphons, and gonophores are arranged around the very much shortened 

 stem in successive whorls. But Schneider, arguing from Haeckel's figures, has 

 attempted to show that the supposed whorls are only superficial, and that the 

 palpons, siphons, and gonophores of Nectalia are in reality in a continuous line 

 as in other Agalmidae, except that the line is twisted in a spiral as it is in Physo- 

 phora. This explanation would fit in nuich better with the actual conditions 

 in the Agalmidae on the one hand and the Physophoridae on the other, and the 

 only example of the genus which I have been able to examine lends support to 

 it so far as its rather imperfect preservation allows me to judge. The exact 

 arrangement of the various appendages is described below (p. 290). 



The agreement between Nectalia and the other Agalmidae in the structure 

 of the pneumatophore and nectosome, in the bracts and in the individual append- 

 ages of the siphosome is too close to allow any conclusion other than that it is 

 an offshoot of that family. Indeed the only important feature by which it is 

 separated from the latter is the very much shortened stem. For this reason 

 Schneider has united it with the Agalmidae, instead of following Haeckel ('88b) 

 and Chun ('97a, '97b), who have regarded it as a distinct family. 



Nectalia and Physophora have diverged from the parent stock, Agalmidae, 

 along lines similar so far as the shortening of the stem is concerned. But the 

 condition of the bracts seems to negative the possibility that the two stand in a 

 direct generic series, because they are entirely aborted, in Physophora, whereas 

 in Nectalia they are specialized to an unusual degree. This difference between 

 Nectalia and Physophora is even more significant than is the presence of a 

 secondary porus in the pneumatophore of the latter, contrasted with the absence 

 of such an opening in Nectalia. In the one case, i. e., that of the bracts, we have 

 to do with the specialization in opposite directions, regressive and progressive, 

 of organs existing in the parent; in the other with the formation of a new organ. 

 And of course we can as easily conceive of the porus as appearing de novo in Physo- 

 phora, as in one of its ancestors. 



