«S, F. Clark on Keio ami Bare K<pecies of Ih/drokU. ui 



Gonothyraea tenuis, sp. nov. 



Plato X, tig. 8. 



Stem simple, somewhat iiexuous, slender, and aniiulated ahovc the 

 origin of each of the numerous branches, wliich are an-auged alter- 

 nately, some simple and some compound, the latter l)earing numerous 

 brancldets, the lower branches sometimes half the length of the main 

 stem ; base of the stem and of the lower branches light horn-color, 

 the ui)])er portions of the same and all of the brancldets jjellucid 

 white; branches and branchlets spreading, giving quite a bushy ap- 

 pearance to a Avell develo])ed colony. Hydrotheca' variable in size, 

 deeply campanulate, tapering quite rapidly from a little below the 

 middle to the base ; the rim is ornamented with teeth which show 

 considerable variation, both in number and in shape ; in some cases 

 they are quite sharj) and shallow, while on other calycles upon the 

 same stem they are of a castellated form and sometimes slightly 

 emarginate ; in number they vary from ten to sixteen; the i)edicels 

 which support the hydrotheca? also vary greatly, some being com- 

 posed of but three or four annulations, others of as many as fourteen. 



Gonothecge axillary, very much elongated, narrow, obconic, taper- 

 ing gradually from the distal to the proximal end, borne on short 

 pedicels of but three to live rings ; the nnmber of medusa? holding 

 planuhe contained in each reproductive capsule varies from two to 

 five and the number of planula^ in each medusa varies to the same 

 extent ; the tentacles of the medusa? vary considerably in length 

 and in number, some of them being over half as long as the diameter 

 of the medusa, Avhile others are not more than one-third that length, 

 in number they vary from eight to fourteen. The planuliB at the 

 time of liberation are regularly cylindrical, and their length is equal 

 to nearly foiir times the width. Height usually 1 to 1-25 inches (25 

 to 38'""^). 



New Haven, Conn., on piles of Long Wharf, June 2nd, 1875,— 

 S. F. Clark. Found in consideral)le abundance at low-watei', loaded 

 with reproductive capsules. The large size of the latter, together 

 with the clusters of extracapsular medusa, make this quite a showy 

 species for one of such humble growth, 



Opercularella pumila, sp. nov. 



Plate IX, figs. 3, 4, 5. 

 Stem rather stout, erect or creeping, slightly flexuous, amudated 

 throughout, sparingly branched ; branches erect, undivided, some- 



