Chap. VII. 



LAOMEDEA AMPHORA. 



311 



Fig. 49. 



Fig. 48. 



eter of the whole bell ; but it thins out toward the actinal end {c), where 

 it terminates in a rather blunt edge ; and the aper- 

 ture (a) of the veil occupies a little more than 

 one half the whole lateral extent of the actinal 

 end of the disk. The oldest medusa, still in the 

 progress of growth, which we have studied, was one 

 fifth of an inch across the actinal 

 margin (wood-cut 48), and bore eighty 

 variously-developed tentacles, of which 

 four were primary, and nineteen sec- 

 ondary, in every quarter segment of the disk. The shape of the disk 

 had approached near to that of the adult (wood-cut 49), which is 

 a deep saucer form, and the veil was reduced to about the same proportions as 

 in the adult, being one eighth the breadth of the actinal end of the disk. 



TiAROFSis with eighty tentacles. 



Adult TiARorsis 



DIADEMATA. 



SECTION V. 



LAOMEDEA AMPHORA AG. 



Proles hjdroidea. Adult. — This hydromedusarium (PI. XXX. Figs. 1, 2, and 3) 

 may be found in any of the rocky tide-pools along our coast, attached either to 

 searweeds or to the shells of stationary mollusca. It is one of the most hardy 

 of the Campanularians, but we cannot say that we have ever seen it left out of 

 the water entirely, and only covered, like Dynamena, with dripping Fucus pendent 

 from the sides of rocks and boulders. It usually grows to a length of three or 

 four inches, but occasionally may be found five or six inches long. The orien- 

 tation of the branches is the same as in Obelia commissuralis, excepting that the 

 branches do not diverge nearly at a right angle, as in that species, but at about 

 thirty-five or forty degrees. The rings at the base of the branches are often 

 more numerous than in the above-mentioned species, but the most marked difference 

 is in the middle of each internode {Fkj. 11, c^), where it bulges laterally, and 

 directly in a line with the point of insertion of the branch or pedicel below it. 

 The pedicels are ringed throughout, and the older ones {Fig. 14, (?) are very 

 deeply constricted. The calycle of the hydra is campanulate, and from one third 

 to two fifths deeper than broad, and the edge is slightly polyhedral, usually twelve- 

 sided {Fig. 6*). The wall is very thin; at the base it has the same thickness as 

 that of the pedicel, but thins out to a mere film at the edge. The partition 



