ABYLA LEUCKARTII. 217 



Station 4671 300 fathoms to surface 1 anterior nectophore 

 " 4fi7fi " " " " " " " 



" 4707 " " " " " " " 



" 4708 surface; 2 specimens with both anterior 



and posterior nectophore. 



The largest anterior nectophore is 9, the smallest 4 mm. long. The pos- 

 terior nectophore is 4.5 mm. long. 



Abyla leuckartii has been recorded twice since it was described by Huxley 

 with a total of eleven specimens; and of the two described by Agassiz and Mayer 

 (:02, p. 165) one, from its "narrow elongated, five sided" pyramidal form, 

 certainly does not belong here. The description of the nectosac as long and 

 tapering to a point near the apex of the bell, as well as a sketch from life sub- 

 mitted to me by Dr. Mayer, shows that the individual in question was in reality 

 a Diphyabyla. 



The external form of the anterior nectophore of this species, which is so 

 characteristic that there is no danger of confusing it with any other Siphono- 

 phore, has been well figured by Lens and Van Riemsdijk, and its ridges and facets 

 described by them in great detail. As a guide to identification the following 

 brief account is given. 



The nectophore is pentagonal in side view; the upper portion rectangular; 

 slightly longer than broad, and laterally compressed. The ridges are 2 dorsals, 

 2 laterals, 2 ventrals, and two which bound the roughly rectangular apical 

 facet. The two ventral ridges come together basally to form a single tooth, 

 and each of the two dorsal ridges ends in a large basal tooth. There is also a 

 prominent triangular tooth on each side interrupting the basal margin of the 

 nectophore opposite the dorsal face of the hydroecium. But the lateral ridges 

 instead of reaching these teeth terminate some distance above them. These 

 lateral ridges follow a characteristically curved course. The basal parts of all 

 the ridges are strongly serrate in the present specimens, but apparently less so in 

 the "Siboga" material. The nectosac is cylindrical, and reaches nearly to the 

 apex, as does the hydroecium (Plate 13, fig. 5). The somatocyst is very large, 

 ovoid, its long axis lying nearly apicobasal. At its upper end it connects with 

 the stem by a narrow canal. Up to the present time the species has been known 

 from anterior nectophores only, and Schneider has referred it to Enneagonum 

 ( = Cuboides) on the assumption that no posterior nectophore occurs. Two 

 specimens in the present series (Plate 13, fig. 5) with small posterior necto- 

 phores still attached, and others with easily distinguishable reserve buds were 



