194 AMPHICARYONINAE. 



The Eudoxid. The Eudoxids of N. diomedeae (Plate 1, fig. 5) rival in size 

 the " Ceratocymba " of Abyla leuckartii, the bract of the largest specimen being 

 33 mm. long. But these enormous bracts, except for size, and for minor details 

 as to the branching of their canals, resemble so closely the bract described above 

 that there is no doubt that they belong to the N. diomedeae. Thus they are 

 of the same triangular, laterally flattened form, show the same basal hydroecial 

 cavity, and similar basal gelatinous prominences. The canal system consists 

 of the same four main trunks. The odd basal one now gives off three or four 

 short transverse branches, the apical trunk from four to six, already foreshadowed 

 in the young bract. The branching of the paired hydroecial trunks is now 

 more complex than it was in the young stages already described. Furthermore 

 it is asymmetrical as in the adult nectophore. Here, as in the latter, the branch- 

 ing of the canals shows a good deal of individual variation. It is easily derived 

 from the condition in the young bract as the result of growth, a conclusion sup- 

 ported by the fact that its branching is progressively more and more complex 

 in larger and larger specimens. 



The gonophores show little change except for the much greater size, from 

 the form described above for their earlier stages. In each of the Eudoxids there 

 is one large gonophore, either male or female, and one or two buds for future ones. 



The siphon, which has a well-marked basigaster (Plate 1, fig. 6), is of the 

 usual type. 



The tentilla are of the form described above. The agreement between 

 their structure, and those of the cormidia of N. diomedeae while still attached 

 to the stem is a further reason for uniting these Eudoxids with that species. 



Prayidae Kolliker, 1853. 



Diphyidae Chun partim. 



Amphicaryoninae Chun, 1888. 



This subfamily is treated first of the Prayidae because the failure to develop 

 more than two nectophores or even additional reserve buds, clearly shows that 

 it has departed but little from its Monophyid ancestors. In the more highly 

 specialized members of the family the older nectophores are successively dropped 

 as new ones develop, the number thus remaining approximately constant. 

 In the Amphicaryoninae, however, the older of the two nectophores is retained 

 permanently, but decreases both in relative size and in function. 



