24 



As soon as we had found these differences the selection of the very extensive material 

 of both Abvlopsis quincunx and Abyla pentagona was extremely facilitated. 



The remains of stem and appendages in superior and inferior nectophore were hardly 

 to be recognized; at any rate the appendages were not well enough preserved to show the 

 structure of the bract, a very important thing for the determination of the eudoxids. We therefore 

 hardly feel justified as jet to consider Aglaismoides Eschscholtzi Huxley as the eudoxid of 

 Abylopsis quinninx, though we are inclined to do so, as the Siboga material contains many 

 specimens of this eudoxid^ there being at the same time except Aglaisiiia cuboides Lkt., Sphcnoidcs 

 australis Huxl., Amphiroa alata Les., no other eudoxids of Ahylids in the collection. 

 The inferior nectophore. 



The striking difference, at first sight, between the inferior nectophores of Abylopsis 

 and Ab\la is the greater development of gelatinous substance in the former, the broadness in 

 comparison to the latter where the inferior nectophores are 2^:5—3 times longer than the superior 

 and finally the mode of attachment and the outward appearance of the superior part of the distal 

 nectophore (compare our sketches PI. Ill, figg. 22, 23 with the sketches given by KOll. 54, 

 Lkuckart 54, etc. for Abyla pentagona). 



As the gelatinous substance has so much increased in size, the result is a different aspect 

 of the ba.sal facet, taken when the whole specimen rests on the anterior pentagonal facet of the 

 superior nectocalyx (fig. 27). The whole basal part of the inferior nectophore is very different 

 from the same in Abyla as is shown in fig. 20. It is clearly shown how the basal ridges are 

 convex in Abvlopsis, less in Abyla. But the real absolute distinction between Abylopsis and 

 Abyla is found in the canals of the inferior nectocalyx. 



We gave above a description of the course of these canals in Abyla pentagona (see p. 20). 



We have looked in vain for this same structure in all 35 inferior nectophores oi Abylopsis. 

 Here they have quite a different course. Anteriorly there are none but the two proximal canals, 

 first following the superior wall of the nectosac. They do not reach its proximal wall but bend 

 down on the side w^all and reach the velum on the right and left side of the proximal half. 

 The two other canals are situated in the hind wall and run nearer to each other. They meet 

 in the basal part of the nectosac forming an enlargement which is very much developed. 



Chun never mentioned this very characteristic difference between this structure in Abylopsis 

 and Abyla and it is especially this difference in structure of the canals which prompts us to 

 consider Abylopsis qtiincunx Ch. as absolutely different from Abyla pentagona O. et G. 



Huxley described (59 p. 49, PI. II, fig. 2) an Abylid which he considers to be an Abyla 

 pciitago7ia. Later authors Haeckel 88 a and Chun 88 and 97 b, Mayer 98, A. Ac. and M.\yer 

 1900 consider those specimens to be different. Haeckel calls it Calpe huxlcyi (88 p. 164). 

 Chun finds his atlantic Abylopsis quincunx identical with Huxley's Abyla pentagona. It might 

 be of ereat value to know the exact course of the canals in the nectosac of the inferior 

 nectophore. Unfortunately Huxley gives no description of them. He refers to Kolliker (59 p. 43). 

 So we draw the conclusion that the)- are similar to those in Abyla pentagofta. Then of course 

 the identification with Abyla pentagona would be justified. Huxley's specimens would be simply 

 the smaller ones, as we found them also in our material for Abyla pentagona (see p. 20). 



