REPORT ON THE SIPHONOPHOR^. 165 



the latter separating them like the ridge of a house-roof. The middle of the coryphal 

 edge is nearly in contact with the oleocyst (co). 



The two infero-lateral faces of the first nectophore are much larger, and of a more 

 complicated form, sexangular ; the ventral half of their larger quadrangular upper part 

 being prolonged into an obliquely quadrangular descending plate of half its size (fig. 8) ; 

 this plate forms the lateral wall of the hydroecium (ui). The inferior dorsal angle of 

 this plate (between the openings of the hydroecium and the nectosac) is the lowermost 

 point of the first nectophore ; it marks the basal pole of its principal axis, whdst the 

 apical pole of the latter is formed by the opposite oleocyst (co), and the centre of the 

 coryphal edge (nk). 



The inferior or the proper basal face of the first nectophore (opposed to the coryphal 

 crest, nk, fig. 8) is divided by a prominent frontal septum (nt) into two divergent 

 obliquely ascending secondary faces ; the dorsal or posterior of these is quadrangular and 

 contains the opening of the nectosac (fig. 6, uo) ; the ventral or anterior is pentagonal 

 and contains the mouth of the hydroecium (fig. 7, inferior third). The basal edge of 

 the frontal septum is emarginate. 



First Nectosac (figs. 5-8, tv). — The subumbrella of the apical or proximal nectocalyx 

 occupies its dorsal half, and is separated by the frontal septum from the ventral parts, 

 the somatocyst (cs) in the upper, and the hydroecium (ui) in the lower half. The 

 nectosac is subcylindrical, four times as long as broad ; its closed upper end is near the 

 dorsal end of the coryphal crest (nk) ; the ostium of its lower end (uo) is surrounded by 

 a small velum, and opens in the dorsal half of the basal face. 



Canals of the Nectosac (figs. 5-8). — A nectocalycine duct (en) arises from the apex 

 trmici or the top of the hydroecium, and ascends obliquely to the dorsal face of the 

 nectosac (fig. 8, 10). It divides here into four radial canals ; the shortest is the 

 descending ventral canal of the nectosac, the longest the opposite dorsal canal (fig. 6, eel), 

 both placed in the median place of the nectophore ; intermediate in size are the two 

 paired lateral canals (right ex, and left cl) ; these form a small arch in their upper part. 

 A far larger arch is formed by the dorsal canal, which ascends to the top of the nectosac 

 and descends along its whole dorsal median line. 



Hydrcecium (fig. 7, ui, ventral view ; fig. 8,ui, lateral view from the left side). — The 

 hydrcecial or funnel cavity is campanulate and occupies the basal half of the ventral 

 part of the first nectophore. Its rounded apex is closed and from it arise the two 

 small canals running to the nectophore and the somatocyst. The larger dorsal wall of 

 the hydroecium is formed by the frontal septum (nt), which separates it from the neigh- 

 bouring nectosac. The smaller ventral wall is deeply emarginate (fig. 7). The inferior 

 opening of the hydroecium is quadrangular, obliquely truncated, with four prominent 

 points or teeth. The two dorsal teeth are the inferior corners of the frontal septum, and 

 much stronger than the two ventral teeth. 



