Dr. C. Chun on the Siphonophora. 155 



detection of the second nectocalyx. As Busch describes a 

 form evidently identical with Diphyes Kochii as Maggicea y in 

 consequence of supposed differences, I combine the names 

 selected by the first observers, and designate the Siphono- 



phoran as Muggicea Kochii. 



As regards its structure, which I afterwards had the oppor- 

 tunity of examining more accurately in Naples, the elevated 

 flask-shaped nectocalyx exactly resembles the nectocalyx of a 

 Diphyid (fig. 2). It is furnished with five wing-like edges, 

 two of which are more considerably developed towards the 

 margin of the bell and bound a funnel-shaped space, within 

 which the stem with its appendages can be retracted. The 

 nectosac, consisting of transversely striated spindle-shaped 

 muscle-cells, lines the subumbrella, and terminates at the 

 margin of the bell in a very contractile velum. On the dila- 

 ted side of the nectocalyx, above the funnel-shaped gelatinous 

 mantle [hydroecium], we easily observed the so-called fluid 

 receptacle [somatocyst, Huxl.], with its oil-drop, an organ 

 which has received the most various interpretations, but, in 

 my opinion, without the right one having been hit upon. I 

 regard it as a hydrostatic apparatus, destined, by means of 

 the specifically lighter oil-drop, to present in some degree a 

 counterpoise to the heavy stem with its appendages, and to 

 keep the nectocalyx in an approximately vertical position. 

 From the base of this fluid- or oil-receptacle originate four 

 vessels (overlooked by Will and Busch), which are situated 

 beneath the musculature of the subumbrella, and open into an 

 annular vessel close to the margin of the nectocalyx. Two 

 of these vessels run upwards on the side-walls, then bend 

 round in an elegant curve, and descend towards the margin ; 

 a third attains the summit of the subumbrella, and opens into 

 the annular canal opposite to its place of origin ; while the 

 corresponding fourth vessel forms only a very short branch of 

 union between the latter and the issue of the above-mentioned 

 [annular] vessel. Both the vessels and the fluid-receptacle 

 open into the contractile stem of the whole colony [hydrosoma] 

 with its polymorphic groups of appendages. In general this 

 is not very long ; I have not observed on it more than twelve 

 groups of individuals. The latter regularly diminish in size 

 from the base of the stem to its distal extremity. Originally 

 they consist of four buds lined with endoderm, the largest of 

 which develops into a stomachal sac, while two smaller ones 

 placed above it represent the rudiments of the bract and of 

 the genital nectocalyx ; the fourth, which is situated at the base 

 of the stomachal sac, and is early much divided at the surface, 

 becomes differentiated into the tentacle with the urticating 



11* 



