304 HYDROID^. Part IV. 



seemingly prolonged till it equals the length of a pedicel, and then a new calycle 

 is developed, with a regenerated hydra head. 



SECTION II 



CLYTIA (TROCHOPYXIS) BICOPHOBA AG. 



Proles hydroidea. Adult. — The habitat of this species is the same as that of 

 C. poterium, but it is not so abundant as the latter. It may be found from 

 Grand Menan Island, at the extreme eastern coast of Maine, all along the New 

 England coast, to Vineyard Sound, south of Cape Cod. The main stem (PL XXIX. 

 Fig. 6, g) is stolonic, and either smooth or tortuous, while the pedicels (A-G), 

 which arise from it at right angles, are more or less distinctly ringed, from base 

 to apex. At some points the rings are twice as broad as deep {Fig. 7, c^), at 

 others they are equal in breadth and depth, and so on in all intermediate pro- 

 portions. Occasionally the pedicels are branched, not only once {Fig. 6, B), but 

 twice and three times {Y a b c); but as this is not a common occurrence, and, 

 moreover, since now and then a gemmiferous calycle (E, d) arises from the ped- 

 icels, we are inclined to look upon the branching pedicels in the light of erect 

 stolons, if such a distinction can be made. 



As regards size, this species is, on the average, a little smaller than C. poterium, 

 but the most luxurious specimens {Fig. 6) fully equal the latter. The calycle 

 {Fig. 7) of the sterile hydra is deeply campanulate, and the depth compares to the 

 breadth as three to two {Fig. 6). When the hydra is retracted, the sides of the 

 calycle are more or less collapsed {Fig. 7), and then the jjroportions between its 

 depth and breadth are more nearly as two to one. The edge of the calycle is 

 deeply indented {Figs. 7 and 7^ &), or scalloped, into twelve or fourteen divisions, 

 and broad triangular teeth (c") alternate with the sinuses {&). When the calycle 

 is entirely empty, or the hydra is fully expanded {Fig. G, F), the outline of the 

 edge is circular; but when the hydra is contracted, the calycle becomes folded 

 longitudinally {Figs. 7, 7*, and 7*") in such a manner that the teeth (c^) correspond 

 to the broad furrows, which are depressed inwardly, whilst the sinuses {c') project 

 sharply outward, along with the ridges which bound the furrows; and thus, in 

 a view from the end of the calycle, the teeth form the sides of a spherical 

 polyhedron, and the sinuses constitute the projecting angles. At the base, the 

 wall of the calycle is about as thick as that of the pedicel, but it gradually 

 thins out toward the edge. The semi-partition {Fig. 7, c) is no thicker than the 



