REPORT ON THE SIPHONOPHOR^. 157 



are also nearly vertical ; whilst the two terminal faces (superior and inferior) bear a 

 pyramidal apophysis. 



The six lateral faces are two odd and four paired. The dorsal odd face (fig. 7) covers 

 the nectosac, and is nearly rectangular, twice as long as broad, its superior edge a 

 little longer than the inferior. The opposite ventral odd face, covering the somatocyst 

 (fig. 6, uv) is smaller, isosceles triangular, three times as long as broad ; the apex of the 

 triangle is directed downwards, the two lateral edges are convex. The two paired ventro- 

 lateral faces (fig. 5, cs) are quadrangular, their dorsal edge longer than the parallel ventral, 

 and the straight superior edge smaller than the concave inferior. The two paired dorso- 

 lateral faces cover the lateral sides of the nectosac (fig. 5, iv), and are hexagonal ; their 

 two parallel, nearly vertical, lateral edges are two to three times as long as each of the 

 two superior or the two inferior edges. 



The apical or superior face (fig. 3) of the hexagonal prism is not a simple face, but 

 divided by a prominent transverse frontal crest (fig. 3, ut) into two unequal apical facets, 

 a dorsal and a ventral. The dorsal apical facet is far larger, and covers the apex of the 

 nectosac (fig. 3, w 1 ) ; it is hexagonal, with two odd and four paired edges ; the odd dorsal 

 and ventral edges (ut) are parallel and of equal length ; they are longer than the two 

 ventro-lateral, and smaller than the two dorso-lateral, deeply emarginated edges. 



The ventral apical facet is quadrangular, much smaller, and covers the top of the 

 somatocyst (fig. 3, cs). Its two lateral edges are twice as long as the inferior and 

 superior edge (fig. 3, ut), and are so deeply emarginated that the facet appears to be 

 nearly bisected by a frontal constriction. 



The basal face of the hexagonal prism (fig. 4) is also divided by a prominent transverse 

 frontal crest into two unequal basal facets, a dorsal and a ventral. The dorsal basal facet 

 is square, and contains the opening of the nectosac (fig. 4, iv 1 ). The ventral basal facet 

 contains the opening of the hydrcecium (fig. 4, ui), and is isosceles triangular ; the apex 

 of the triangle is directed ventrally, and meets with the apex of the triangular ventral 

 face (fig. 6, cs). 



The interior of the first nectophore contains the nectosac (w) in its dorsal third, the 

 somatocyst (cs) in its ventral third, and between both the hydrcecium (ui) in the middle 

 third. The longitudinal axes of these three organs are nearly parallel, a little con- 

 vergent towards the apex (fig. 5). 



Nectosac (figs. 1 and 5, w, from the right side ; fig. 7, w, from the dorsal ; fig. 3, 

 from the apical ; fig. 4, from the basal side). — The subumbrella is subcylindrical, four times 

 as long as broad ; it occupies the dorsal third of the first nectophore, and is separated by 

 a very thin frontal septum from the adjacent hydrcecium. The nectocalycine duct is 

 very short, and enters into the bent apex of the nectosac, so that the four radial canals 

 of the latter are very regular, and of nearly equal length. The basal opening of the 

 nectosac is very small, and surrounded by a small velum (fig. 4, v). 



