NECTODROMA DUBIA. 205 



general form of the nectophore is nearly cylindrical, truncate so obliquely at 

 the base that the ventral wall extends below the level of the opening of the 

 nectosac. Our example is proportionately longer and narrower than Quoy 

 and Gaimard's figure; but as these authors expressly state that the gelatinous 

 substance is very soft, this difference is merelj' an evidence of contraction or 

 of preservation. The hydroecial groove is deep, and runs the entire length of 

 the nectophore, though it is partially closed over anteriorly by a small gelatinous 

 flap, and is enclosed by two lateral flaps, as Quoy and Gaimard observed. 



The somatocyst, as noted above, strongly suggests the corresponding struc- 

 ture in Stephanophyes superba ; indeed, it was on the strength of this resemblance 

 that Schneider believed that the two species were identical, a possibility negatived 

 by the subumbral canals. Below the point of origin of the pedicular canal 

 it runs as a single unbranched tube, along the dorsal surface of the hydroecium, 

 to a point slightly below the bell opening. Its ascending trunk, however, splits 

 into three branches near the anterior end of the nectophore, the median branch 

 running directly dorsad (Plate 3, fig. 8) and the two laterals (Plate 3, fig. 9) 

 curving posteriorly, with several minor lateral branches, to terminate slightly 

 above the apex of the nectosac. Except for the exact positions and lengths of 

 the minor branches, this agrees very well with the original account of the species. 



The most interesting feature of N. diibia is afforded by the subumbral canals. 

 These were described by Quoy and Gaimard as being numerous, and running 

 radially, as they do in various Medusae. And in the present specimens the 

 subumbrella surface is ribbed radially (Plate 3, figs. 8, 9), precisely as they 

 represented it. To determine whether these ridges do actually represent canals, 

 I cut transverse serial sections of three, and on examination found that each was 

 provided with an open lumen surrounded by a distinct laj'er of entoderm. The 

 precise number of canals could not be determined because in each case one side 

 of the nectosac was torn. Apparently there are twelve at the apex of the bell; 

 and these branch so that there are about thirtj'-five at the margin. The number 

 and arrangement of the canals distinguishes Nectodroma from all other Siphono- 

 phores as yet known. 



Stem and appendages. Though a considerable length of spirally coiled stem 

 is still intact, all of the appendages except a large number of proximal buds 

 have been stripped off. It is important to note that in addition to the large 

 and well-preserved muscular lamella to which the older nectophore was attached, 

 there is a third much smaller lamella which probably bore a "reserve-bell " in life. 

 Of course from the present material it is quite impossible to make out whether 



