BIGELOW: THE CTENOPHORES. 379 



tentilla, and the tentacle-bases and -sheaths agree no better with the 

 young palmata than do those of the adult hormiphora. Chun him- 

 self says ('98, p. 18) " Die Beobachtung des lebenden Thieres wird erst 

 einen sicheren Entschied liefern, ob dieser .... Cydippiden den oben 

 geschilderten Jungendformen zugehoren." The young "palmata" 

 was taken in the Straits of Gibraltar. 



But even though I believe Chun's young "palmata" is a stage in 

 the development of H. hormiphora, the name palmata is not to be 

 abandoned, but must be applied to the adult Hormiphora described 

 by Chun under that name, which proves to be an important and 

 widely distributed species. 



If we turn now to the Indo-Pacific Hormiphoras, of which ochracea 

 has already been treated, we find that two of them, amboinae and 

 japonica, closely resemble Chun's adult palmata, and the same is 

 true of the large Eastern Pacific series. All of them are ovoid in 

 general form, flattened but slightly, if at all, in the pharyngeal plane 

 and they are proportionally much longer than H. hormiphora. In all 

 of them the adradial canals join the meridionals at about the level 

 of the funnel, or very slightly above it; the tentacle-sheaths are 

 closely apposed to the gastric tract throughout their length and 

 reach about to the end of the meridional canals, and open above the 

 level of the funnel; and all have filiform tentilla. 



The characters separating palmata, amboinae, and japonica from 

 one another are the precise height at which the tentacular sheaths 

 open to the exterior, the exact outlines of the sheaths and of the bases 

 of the tentacles, the form of the apex, whether truncate or not, and 

 the proportional length of meridional canals and ribs. But the very 

 large series collected by the "Albatross," which I examined both in 

 life and after preservation, show that all these characters are variable, 

 both normally and with contraction, and that the conditions illus- 

 trated by the three forms are well within the limits of variability of a 

 single species. 



In amboinae the sheaths open close to the apex, which is truncate; 

 in palmata they are only about one third the distance from funnel to 

 apex, japonica is intermediate between the two, and our specimens 

 afford further connecting links; while the truncation of the apex in 

 amboinae is a contraction-phase, paralleled by many of our examples. 

 The outlines of the sheaths are equally variable, being more or less 

 voluminous, and so is the form of the tentacular base, which is vari- 

 ously curved, or straight. These features are much affected by pres- 

 ervation — furthermore, as shown in the figures (Plate 1, fig. 5, 6), 



