HYBOCODON. 



193 



Kir. -.m. 



developed, the long tentacle (Fig. 824) attaining a size two or three 

 times the length of the l)ell ; the prol)oseis 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 maunt'i- 

 as to appear like heavy rings surrounding the thinuei- 

 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- 

 drarium has not been observed, yet their similarity to the 

 most advanced Medusae buds observed on our Cor3'mor- 

 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.) 



Massachusetts 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 Ag ASS. Cont. Nat. Hist. U. S., IV. p. 343. 18G2. 



Hybocodon prolifer Agass. 

 1862. 



Hybocodon prolifer Agass. 



Cont. Nat. Hist. U. S., IV. pp. 243, 343, PI. 23*. Figs, in, ii ; PI. 25. 



Fig. 325. 



This is one of the few kno^vn Tubularians 

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

 acter of the Medusas is particularly important 

 in a morphological pomt of view, giving us, as 

 it does, the clew to the probable 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 Medusa} (Fig. 328), similar to the parent 



Fig. 324. Medusa of Corymorpha, seen in profile. 1, long odd tentacle ; 2, pair of tentacles , 

 3, short odd tentacle. 



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

 tentacles ; d, d, advanced Medusae buds ; a, stem. 



NO. II. 25 



