320 THE VOYAGE OF H.M.S. CHALLENGER. 



spherical cnidocysts, a proximal and a distal. The cnidocysts, which are contained in the 

 middle ampullaceous dilatation of the odd median club (ta), are twice as large as those in 

 the five other cnidonodes. The three terminal branches of the tentillum are solid, rather 

 rigid cylinders, composed of a single column of large hyaline entoderm-cells, with a thin 

 exodermal envelope similar to those of many hydropolyps and of the Narcomedusse. 

 The canal of the tentillum ends at the base, from which the three branches arise ; its 

 surface is covered with papillas (fig. 9, ts). 



Gonodendra (figs. 1 , 2,g). — The single large gonodendron, which is attached to each node 

 of the stem, immediately beyond the insertion of each siphon, has a bright golden-yellow 

 colour. It is like a group of clusters and is composed of numerous smaller gonodendra 

 (of the second and third order), the gonostyle being richly ramified. Each smallest group 

 (or secondary gonodendron) is composed, as usual, of a single medusiform gynophore 

 and a corona of club-shaped androphores, with a distal (rose-coloured) palpon. (Compare 

 PI. XXIII. fig. 8, and pp. 313, 328.) 



Genus 68. Linophysa, 1 Haeckel, 1888. 

 Linophysa, HkL, System der Siphonoplioren, p. 45. 



Definition. — Rhizophysidse with loose cormidia, the gonostyles being attached to 

 the internodes of the stem, between the siphons. Tentacles simple, without tentilla or 

 lateral branches. 



The genus Linophysa is represented by a single species only, inhabiting the depths of 

 the Atlantic between 800 and 1600 fathoms, and captured several times by Studer, who 

 described it under the name Rhizophysa conifera (40, p. 4, Taf. i. figs. 1, 2, 4, 7, 13-18). 

 It differs from all other Rhizophysidse in the simple form of the long tubular tentacles, 

 which bear no tentilla or lateral branches. The siphons possess sixteen black liver-ridges 

 (while the other Rhizophysidse possess hepatic villi). The strobiliform gonostyles seem to 

 alternate with the siphons, the cormidia being loose. Each gonostyle bears, like 

 a fir-cone, a spiral row of imbricated gonodendra, each covered by a scale (gonopalpon ?). 

 These and other structures described by Studer are so peculiar that Linophysa conifera 

 may be perhaps the type of a separate family — Linophysidse. 



Genus 69. Nectophysa, 2 Haeckel, 1888. 



Nectophysa, Hkl., System der Siphonophoren, p. 45. 



Definition. — Rhizophysidse with loose cormidia, the gonostyles being attached to 

 the internodes of the stem, between the siphons. Tentacles branched ; tentilla simple, 

 not branched. 



1 Linophysa = Filament-bladder, fc<W, <pw«. 2 Nectophysa = Swimming-bladder, ufam;, (piacc. 



