NO. 1706. CCELENTERATES FROM LABRADOR, ETC.—BIGELOW. 311 



is one that can be answered only after a study of the development 

 of these organs. It is certain, however, that in the adult the sexual 

 organs are entirely discontinuous along the narrow line of attachment 

 of the mesenteries to the manubrium, as well as in the interradii. 

 In other words, in the adult the sixteen sexual masses are adradial. 

 They may, however, be formed by the fission of eight primary gonads. 

 Maas, in discussing the probable relationship of this genus, especially 

 to Crossota, has suggested that possibly the eight radial ridges of the 

 manubrium which bear the gonads are in reality basal dilations of 

 the radial canals, so that ' ' die 8 Aussackungen die die Gonaden versor- 

 gen, dem Boden der Radiarkanale entsprechen, auch wenn letztere 

 selbst, wie die Schnittbilder Browne's lehren, davon ganz anabhiingig 

 verlaufen" (:06, p. 483). But the conditions in the adult seem to me 

 to lend no actual support to such a view, although a study of the 

 development of the species may give a different result. 



No sense organs were to be found in the present specimens. 

 Browne, however, observed them, and found that their number was 

 probably sixteen. 



Tentacles. — I can add nothing to Browne's account except to note 

 that in one specimen there is a single very large filiform tentacle about 

 twice as long as the bell is high, arising from the tentacular scar be- 

 tween two of the tentacle groups. Allman, in the original account 

 of the species, figured these large tentacles, but in Browne's specimens 

 they were all broken off. 



Ptychogastria yolaris is certainly not an abyssal form, since all 

 recent records of its capture are from comparatively shoal water. 

 It has never, however, been taken on the surface, so far as I know. 

 Judging from the presence of sucking pads on certain of its tentacles, 

 Browne is probably correct in suggesting that it attaches itself to 

 the bottom, as its near relative, Pectanthis asteroides, was seen to do by 

 Haeckel ('81). However, as Browne has pointed out, the high degree 

 of muscular development suggests that the species may be an active 

 swimmer. 



It is not worth while to speculate on the affinities of this remarkable 

 genus until the young stages have been worked out, for only in that 

 way can the nature of gonads and mesenteries be determined. In 

 the meantime we may well follow Vanhoffen (:02) and Maas (:06) 

 in associating it with Crossota, to which it is related by the arrange- 

 ment of the several rows of tentacles. 



Genus AGLANTHA. 



Recent researches on this difficult genus have led most students 

 to agree that in the North Atlantic two species are recognizable, 

 A. digitale, with only four otocysts, of large size, and of Arctic clis- 



