280 HYDROID^. Part IV. 



alcoholic preparations brought home from Key West, in Florida, where our species 

 is common upon the pillars of the wharves, in the harbor of that place. 



The main stem, which is of a very dark brownish-purple color, rises to a height 

 of at least four inches, and at its base is as thick as a common-sized jjin. The 

 root-like stolon is a little thinner than the main stem, and is perfectly smooth, 

 but more or less contorted. The base of the stem is endowed with eight, ten, 

 or twelve nan-ow rings, closely set together, without any intervals ; and the two 

 or three succeeding intervals, just above the origin of the branches, are ringed by 

 several constrictions, but above these each interval has generally only three rings 

 {Fig. 2, A^). The branches {Figs. 1, c, and 2), which are about half as thick as 

 the main stem, have from three {Fig. 2, a) to ten or twelve closely set rings at 

 the base (just beyond the origin of each peduncle they have only three {a^) ), and 

 finally terminate in a peduncle-like expansion (a^), which is made up of from four 

 or five to nine rings. The peduncles {a*) of the hydrae are closely ringed from 

 base to tip ; each successive ring being larger than the preceding, and numbering 

 in all from fourteen to twenty. The base of the peduncles is about one fifth as 

 thick as the branches from which they arise, and the tip of the same has twice 

 this diameter. 



The hydrte, which terminate the ringed peduncles, the branches, and the main 

 stem, are Tubularioid in character, but remind one of Coryne. Imagine the head 

 of a Coryne, with its globe-tipped tentacles, contracted upon itself (PI. XVII. 

 Fig. 6), with a collar of a dozen tapering tentacles, strung around the base in a 

 single row, and we have the hydra of Pennaria. The crown of tentacles, num- 

 bering twelve in all, arises from the tip of the peduncle, without any intervening 

 disk, and spreads its tapering members {Fig. 2, t) equally, all around the base of 

 the head. These tentacles do not come to a point like those of Clava and 

 Hydractinia, but round off, very much in the same way as in Tubularia and other 

 closely allied genera, with an obliquely rounded, slightly globular tip. The head 

 {p p^), which rises from the circle of tentacles, has a remarkable, elongate-ovate 

 shape, bulging to such an extent, on the side {p^) facing toward the main stem, 

 as to render it strongly gibbous (B D E F G); a feature hitherto unnoticed 

 among Hydro-medusje. The oral end {in) tapers, very much after the fashion of 

 a champagne bottle, and is covered by numerous short, globe-tipped tentacles, 

 varying in number, according to the age of the individual, from three or four 

 to thirty-two (D E F G B), and arranged in a spiral combination, similar to what 

 we have described in Coryne. At the base of the gibbous head, and just within 

 the collar of slender tentacles {t), the medusaB {d-d*) bud forth, each one rising 

 directly from the parent, on a short stem {h). We have not seen more than 

 three or four of these, at one time, on any individual head. 



