50 



ooecia, is John Ellis', who in his well-known work on the Corallines not only 

 treats of the hydroid polyps, coral algae, varions Oclacliniae, sponges etc., hnt also 

 of a number of Unjozoa. hi a number of species of the genera Buyiila, liicclUiria 

 and Scriipocellaria he has noticed and figured the ooecia, which he terms « Malls, 

 testaceous Spherules', or »testaceous Figures* '; but while he recognised, although 

 in an imperfect way, the importance of the gonothecae for the reproduction of 

 the hydroids polyps" (»I discovered that they were Matrices or Habitations of 

 young Polyi)es, which are produced here and there, on the Sides of the Parent, 

 as in the Freshwater Polype*), he does not seem to have reached to a similar 

 comprehension of the ooecia. He only speaks in detail about the owcia of a tropi- 

 cal Bmjula species, R. neritiiia ' and expresses here the very remarkable view 

 that they are a sort of small snails, from the eggs of which the colony originates: 

 »I plainlj' discovered it to be the connected Niduses or Matrices of certain testa- 

 ceous Animals, like small snails or Neritae* . . . »()r let us suppose, that the 

 testaceous Animal . . . lays its eggs; these turn into vermicular-shaped Polypes, 

 whicli, after they have fixed themselves to some marine Substance, rise up, and 

 push forth into branches of small Polypes in their Cells«. The oa'cia are thus 

 figured on the accompanying drawings as small .S/j/ror/i/.s- or PUiiiorbis, and from 

 this description Linne gave to this species the name »nerj7i/ia«. Ellis expresses 

 elsewhere a supposition that a similar relation obtains between certain Bripzoa 

 and Bivalves: »The next class, which is the Esclutra deserves our notice» . . . 

 »There appears a great probability of some of these being the Matrices or ovaries 

 of certain Species of Shellfish, perhaps of the Bivalve Kind^ On Flnstra (Eschara) 

 foliacea he further writes"": »Upon examining some specimens lately, I discovered 

 at the Entrance of many of the Cells a small testaceous 13o(ly, like a bivalve 

 Shell «. As appears from the figure to which the writer refers, there is no oa'cium 

 whatever but an oj)en zoa-cial aperture, in which consequently the orifice itself 

 represents the one, the operculum the other sheU. 



Pallas'' suggests the view that the ooecia are ovaries, a view retained to the 

 time of Huxley. It was however chiefly the oa>cia in the incrusting forms 

 (»£sc/ior««), which he was disj)osed to regard in this way, whereas on the other 

 hand he is more doubtful on the question, whether the free plant-like forms 

 ('('.ellahirid ) are provided with such. In iilurimarum, presertim lapidescenlium 

 Eschararnm anli(iuioribus cruslis passim, ad singiilarum cellularum oscula, ohser- 

 vari solet bulla galeae instar cellulae ostio imminens, substantiae Escharae homo- 



' I'J, p. ;!:)— .19. •- 12. Introtiiu-tidii p. IX. ' 12, p. 35. ' 12, liitioduclioii p. XV '■' 12, p. 71. 



pi. XXIX, K. "91, p. :»;. 



