ABYLINAE. 215 



three species with "tetragona" type of anterior nectophore in two, tetragonn 

 and eschscholtzii, the bract is an "Aglaisma." 



In brief, then, Haeckel's three genera, as he defined them, rest on a mis- 

 interpretation of the structure of trigona, and an ignorance of A. leuckartii. 

 But the combined evidence of the anterior nectophore and bract shows that the 

 three divisions recognized by Haeckel and Chun are vahd, though on grounds 

 other than those employed by Haeckel. 



To these must be added Diphyabyla hubrechti Lens and Van Riemsdijk, 

 a form as yet known from the anterior nectophore only. In its essential features 

 it agrees with the corresponding structure in ^4. leuckartii; but its pyramidal 

 external outline, and the form of the nectosac, are so aberrant that it is best 

 retained as a separate genus, at least until its posterior nectophore and Eudoxid 

 are known. This is the only Abylid which can not be connected, even provi- 

 sionally, with any known Eudoxid. 



Most students agree that the species listed by Chun ('97b) are all worthy 

 of recognition; and to them must be added Abijla haeckeli Lens and Van 

 Riemsdijk, closely allied to — A. trigona, hut separated from it by a constant, 

 if minor character. I regret that in the following description two nomenclatural 

 changes have been found necessary: — .4. pentagona Quoy and Gaimard, a name 

 long used, must be supplanted by tetragona Otto (p. 224) ; and quincunx Chun, 

 by eschscholtzii Huxley (p. 227). 



There are three Eudoxids, probably belonging to this subfamily, as yet 

 unconnected with their respective polygastric stages; these are Ceratocymha 

 sagittata (Quoy and Gaimard) Chun, Enneagonoides quoyi Huxle}^ and E. 

 picteti Bedot. 



Key to the polygastric state. 



I. Anterior nectophore with rectangular apical facet; posterior nectophore 

 essentially pentagonal, its hydroecium open; bract of "Amphiroa" tj-pe. 

 Abyla. 



a. Anterior nectophore with one ventrolateral facet on each side; not 

 divided transverse!}'. 



a'. Posterior nectophore with a well-developed ridge on either side; 



somatocyst of the bract recurved at its tip ("Ceratocymba"). 



A. leuckartii. 



h. Two ventrolateral facets, apical and basal, on either side of the anterior 



nectophore. Posterior nectophore with lateral ridge almost suppressed, 



strongly asymmetrical. 



