REPORT ON THE SIPHONOPHOR^E. 223 



and left) are triangular in the proximal half, quadrangular in the distal half, which is 

 separated from the former by an equatorial crest. The distal (or basal) face, which 

 encloses the small ostium of the nectosac (fig. 8, v), is small, and nearly square. 



Nectosac. — The subumbrella, placed in the distal half of the nectophore, is cordiform 

 or hammer-shaped, with an odd distal part bearing the mouth, and two paired lateral 

 parts, which expand right and left ; the three parts are subequal in size and similar in 

 the quadrangular outline, seen from the face. The frontal axis of the nectophore passes 

 through the broad proximal face of its subumbrella. The lateral view of the latter is 

 oblong. The course of the four radial canals is as usual, straight in the two sagittal 

 vessels (shorter ventral and longer dorsal), complicated and bent with three loops in the 

 two paired lateral vessels (compare pp. 189, 216, and figs. 6-13). 



Siphosome (lower half of figs. 2, 3; fig. 1, lateral view, from the left side; fig. 2, 

 dorsal view ; fig. 3, ventral view). — The siphosome of the single specimen observed 

 possessed five fully-developed eormidia, and was in size (length as well as breadth) one 

 and a half times as large as the nectosome ; it equalled the latter in rigidity, and pre- 

 sented a glassy cylinder of 20 mm. in length and 12 mm. in diameter. Its axial trunk 

 was nearly straight, and bore on its ventral median line the five equidistant ordinate 

 eormidia. These occupied in the swimming animal (with horizontal trunk) only the 

 ventral half of the siphosome, whilst its dorsal half was exclusively composed of bracts. 

 All the siphons depended from the ventral side, and the long tentacles were prominent only 

 on this side ; in the same form which I have figured in the case of Crystallodes rigida 

 (84, pi. x. figs. 65, 66). The same characteristic form is clearly represented in an 

 excellent (unfortunately not published) figure of Crystallodes mertensii, drawn from life 

 by Mertens in 1827. 



Cormidia (fig. 4). — Besides numerous buds of undeveloped eormidia, placed at the 

 top of the trunk of the siphosome (immediately beyond the nectosome), there were 

 attached to the ventral median fine of the trunk in the specimen figured five equal, 

 well-developed and equidistant ordinate eormidia. Each of these is composed of the 

 following parts arising from a common base : — (1) a siphon with its tentacle ; (2) a group 

 of four (sometimes three or five) palpons ; (3) a group of bracts (of the same number ?) ; 

 (4) a male gonodendron ; and (5) a female gonodendron. The equal intervals between 

 the cormidia, or the free internodes of the stem, were only covered by thick prismatic 

 bracts, densely attached one to the other. 



Bracts (figs. 1-3, b ; figs. 14-16). — The hydrophyllia are thick glassy polyhedral bodies 

 of cartilaginous consistence, completely transparent, similar to colourless crystals. They 

 are easily detached from the stem, and offer very different forms, partly subregular, 

 partly irregular. The majority are wedge-shaped or obliquely pyramidal, with a 

 tapering proximal end attached to the trunk, and a truncate facetted distal face. The 

 upper face of the bracts is usually somewhat convex, the lower concave, and the outer 



