REPORT ON THE SIPHON OPHOR^E. 139 



Nectophore (fig. 1, basal view; fig. 2, apical view; fig. 3, dorsal view; fig. 4, 

 ventral view ; fig. 5, lateral view from the left side). — The single nectophore (or the 

 apical nectocalyx) has a diameter of 10 to 15 mm., and a complicated polyhedral form. 

 In that position which is regarded as the normal in figs. 3, 4, and 5, the two parallel 

 axes of the nectosac and of the hydrcecium stand vertically. The umbrella of the 

 nectophore appears composed of a quadrilateral pyramid in the apical half, and of a poly- 

 gonal prism in the basal half. 



The apical view of the nectophore (fig. 2) exhibits a rather regular quadrilateral 

 pyramid. Its four perradial edges (the dorsal nd, the opposite ventral or coryphal nk, 

 and the two lateral, right and left) meet in the central apex of the pyramid at right 

 angles. The four faces separated by them are irregularly rhombic, the two dorsal (left ud', 

 and right ud") and the two apici-ventral faces (left ua', and right ua"). Each of these 

 four faces is slightly concave, and in the middle between each two pyramid edges is pro- 

 longed into a descending pyramidal apophysis ; these four basal apophyses alternate 

 regularly with the four pyramid edges, and are of course interradial. 



The basal view of the nectophore (fig. 1) shows that these four interradial basal 

 apophyses are three-sided pyramidal, and that their inferior crests or basal edges are 

 directed radially towards the centre of the basal face. The centripetal end of the basal 

 edge of the two dorsal apophyses passes over directly into the two lateral teeth of the 

 mouth of the nectosac, whereas the centripetal end of the basal edge of the two ventral 

 apophyses finally passes over into the two smaller dorsal teeth of the mouth of the 

 hydrcecium. The four basal faces of the nectophore, which are separated by those four 

 interradial basal crests, are also concave, and have a bilateral-rhombic, or, strictly speaking, 

 pentagonal form. The ventral basal face (uv) is somewhat smaller than the dorsal basal 

 face (itg), and the two pentagonal- lateral basal faces are intermediate between them. 



The ventral view of the nectophore (fig. 4) therefore exhibits the smaller ventral basal 

 face (uv) surrounded by four larger faces (fore-shortened) ; the two ventral basal faces 

 (ux right, id left) and the two ventral apical faces (ua" right, ua' left). The somato- 

 cyst (cs), with its apical oleophore (co), and beyond it the hydroecium (ui), with the 

 included siphosome, appear through the ventral wall of the nectophore in this view 

 (fig. 4). The basal opening of the hydroecium (td) is surrounded by four serrate trian- 

 gular teeth, two smaller ventral and two larger dorsal. 



The dorsal view of the nectophore (fig. 3) exhibits the two large quadrilateral dorsal 

 apical faces (ud' left, and ud" right), and beyond them the pentagonal dorsal basal face of 

 the nectosac may be seen through the dorsal wall of the nectophore, and above it the 

 oleocyst (fig. 3, co). 



Nectosac (fig. 6, w, lateral view, right side ; fig. 5, lateral view, left side ; fig. 3, w, 

 dorsal view; fig. 2, w, apical view; fig. 1, w, and 7, basal view). — The nectosac, or the 

 muscular subumbrella of the nectophore, includes a slenderly ovate cavity, which in the 



