HYBOCODON. 



193 



Fig. 321. 



developed, the loiiiz: tentacle (Fig. 324) .attaining a size two or three 

 times the length of the bell ; the proboscis is long, and stretches be- 

 yond the aperture of the veil ; the long tentacles (1, 2, Fig. 324) are 

 capable of great contraction and expansion ; the lasso- 

 cells are arranged in groups upon them in such a manner 

 as to appear like heavy rings surrounding the thinner 

 thread , the outer wall of the proboscis is exceedingly 

 thick, as in the Medusa of Euphysa, and of a light-yellow 

 color ; the pigment-cells at the base of the tentacles are 

 light pink. This Medusa attains a size of a quarter of an 

 inch, and is found at Nahant in the middle of May. 



Although the separation of this Medusa, from its Hy- 

 drariuni has not been observed, yet their similarity to the 

 most advanced Medusaj buds observed on our Corymor- 

 pha leave but little doubt on this point. Hodge has 

 observed the development of an English species of Corymorpha, which 

 resembles the Medusa here figured. (Fig. 324.) 



Mas.sachusetts Bay, Nahant (L. Agassiz). 



Cat. No. 18, off Race Point, Cape Cod, Mass., March, 1862, A. S. Bick- 

 more. Hydromedusarium. 



Museum Diagram, No. 24, after L. Agassiz. 



HYBOCODON Agass. 



Hyhocodon Agass. Cont. Nat. Hist. U. S., IV. p. 343. 1862. 



Hybocodon prolifer Agass. 



Hybocodon prolifer Agass. Cont. Nat. Hist. U. S., IV. pp. 243, 343, PI. 23% Figs. 10, U ; PI. 25. 

 1862. 



This is one of the few known Tuljularians Fig-sas. 



found growing singly. (Fig. 325.) The char- 

 acter of the Medusie is particularly important 

 in a morphological point of view, giving us, as 

 it does, the clew to the prol)able character of 

 the scales (Deckstiick) of the Nanomia, de- 

 scribed below. The asymmetrical character of 

 the Medusa (Figs. 326, 327) is more marked 

 than in the Medusa of Corymorpha. The bud- 

 ding of Medusae (Fig. 328), similar to the parent 



Fi". 324. Medusa of Corymorpha, .<;ooii !n ])rofite. 1, long odd tcntac-Ie ; 2, pair of tentacles , 

 3, short odd tentacle. 



Fig. 325. Single Hydra of Hybocodon. o, mouth surrounded witli tentacles ; /, ^ marginal 

 tentacles ; (/, (/, advanced Medusa' buds ; <i, stem. 



NO. II. 25 



