BIGELOW: THE CTENOPHORES. 



The best preserved specimens agree in general with the photograph 

 (Plate 1, fig. 1); but one very large example is more spindle-shaped, 

 approaching Agassiz and Mayer's (:02) figure of their fusiformis. 

 The series from Station 4600 are all soft and flaccid, and in most of 

 them the aboral pole is more or less retracted. But these specimens 

 were collected before I joined the ship, and experiments showed that 

 the difference in solidity and outline between them and the specimens 

 collected later were due to differences in preservation. Differences 

 in preservation, especially whether or not the specimens were stupified 

 in chloretone, cause differences in the degree of protusion of the mouth, 

 and in general form and proportions (cf. fig. 1, fig. 2). 



Tentacles and sheaths. The tentacular sheaths are voluminous, 

 and in the better specimens their form (Plate 1, fig. 1) agrees very well 

 with Chun's ('98) figure, and with Moser's figure ( : 08b) of amboinae. 

 But they vary in their precise outlines; in some of the specimens 

 they are narrower (Plate 6, fig. 2), just as Moser (:08a) has figured 

 them for japonica, and there is a series of intermediates connecting 

 the two extremes. The differences are nothing more than contraction- 

 phases. The precise level at which the sheaths open to the exterior 

 is likewise a variable feature, so much so as to be worthless as a specific 

 character unless used within broader limits than the range included 

 in the synonyms of palmata. In the best preserved examples the 

 opening is at a level varying from § to J the distance from funnel to 

 apex (Plate 1, fig. 1). In japonica it is at about § ; in Chun's speci- 

 men it was slightly nearer the level of the funnel. 



In the flaccid specimens from Station 4600 the sheaths open higher, 

 just as they are figured for amboinae (Moser, :08b, pi. 1, fig. 4); but 

 the difference is largely due to the fact that in them, as in amboinae, 

 the apex is more or less retracted by preservation. In two small 

 specimens the level of the tentacular opening is about § the distance 

 from funnel to apex. The series shows that the differences in this 

 respect noted by Moser are not specific. 



In most of the specimens the basal ends of the sheaths fall a little 

 short of the oral ends of the meridional canals (Plate 1, fig. 3, 6). In 

 some, the canals extend even further beyond the sheaths, but on the 

 other hand the sheaths in other examples are longer than the canals 

 (Plate 1, fig. 5) as in Moser's figure of japonica, and in still others 

 sheaths and canals reach about the same level, as in amboinae and in 

 Chun's specimens. 



The size and form of the bases of the tentacles have been used by 

 Moser as specific characters — but both of them vary beyond the 



