REPORT ON THE SIPHONOPHOR^E. 



303 



Height of the conn (vertical axis), without nectophores and tentacles, 



Breadth of the corni (greatest horizontal diameter), 



Height of the pneumatophore (vertical), 



Breadth of the pneumatophore (horizontal), 



Length of the aurophore, 



Breadth of the aurophore, 



Length of the nectophores (with pedicles), 



Breadth of the nectophores (diameter of the umbrella), . 



Diameter of the trunk (vertical and horizontal axes of the siphosome), 



Length of the siphons (much contracted), 



Breadth of the siphons (diameter of the stomach), 



Length of the tentacles (on an average), 



Breadth of the tentacles, ..... 



Diameter of the gonodendra, ..... 



Diameter of the gonophores, ..... 



mm. 

 40 

 60 

 11 

 22 



7 



6 

 20 

 10 

 30 

 10 



3 

 200 



1 

 10 



1 



Figures. — Figures 1, 6, 13, and 14, which represent the complete corm (1 from 

 above, 6 from below, 13 from the left side, and 14 from the dorsal side), are semi-diagram- 

 matic, inasmuch as the detached nectophores are placed in their probable position and 

 form, and in fig. 1 3 the detached tentacles are added. Of course the form and position 

 of the detached nectophores could not be recognised in the spirit specimens with full 

 certainty, the soft jelly-substance being much contracted by the action of the alcohol. All 

 the other figures are drawn exactly from the preparations. 



Nectosome (PI. I. fig. 1, apical view from above; PI. III. fig. 13, superior half, 

 lateral view from the left side ; fig. 14, dorsal view from behind ; PI. IV. fig. 15, sagittal 

 section). — The large pneumatophore (p) is a flattened spheroid, separated from the 

 subjacent trunk of the siphosome by the flat circular hypocystic cavity (fig. 15, eta). 

 The surrounding corona is composed of fifty to eighty (or more) nectophores In), 

 arranged in three alternating annular series (fig. 13); their high lamellar pedicles, 

 however, form a single corona (figs. 14, 16). The corona of the nectosome is 

 perfectly symmetrical, bisected by the vertical sagittal plane ; in the ventral centre 

 of this lies the series of buds (PI. IV. fig. 16, i), in the dorsal centre the auro- 

 phore (/). For the peculiar structure of this latter, compare p. 283, and PI. V., with 

 explanation. 



Si%)liosome (PI. II. fig. 6, basal view; PI. III. fig. 13, inferior half, lateral view 

 from the left side; fig. 14, dorsal view ; PI. IV. fig. 15, sagittal section). — The solid 

 cartilaginous trunk of the siphosome, traversed by a dense network of innumerable 

 canals (fig. 15), is sometimes subspherical, at other times more like a truncated cone. 

 Its entire surface is covered with very numerous, densely aggregated cormidia (fifty to 

 eighty or more). Each cormidium is a conical cartilaginous bulb, and bears a single 

 siphon (s) with a very long tentacle (t), and a clustered gonodendron ; the gonostyle of 

 the latter is originally simple (fig. 3), but often so deeply forked that two separated 



