130 



THE AXATOMY OF INVERTEBRATED ANIMALS. 



condition the gonophores of Athorybia may be cited (Fig. 

 27) ; of the latter, the gonophores of Physalia, Porpita, and 

 Velella. 



In Athorybia, groups of gonophores, together with piri- 

 form sacs, which resemble incompletely developed hydranths 

 (hychocysts — Fig. 27, A, a), are borne upon a common stem, 

 and constitute a gonoblastidium (Fig. 27, A). The groups 

 of male and female gonophores (Fig. 27, A, b, c) are borne 

 upon separate branches of the gonoblastidium (androphores 



Fig. 27.— Athorybia rosacea.— A, gonoblastidium bearing three hydrocysts, a; gyno- 

 phore, b ; and two andropbores, c. B, female gonophores on theircommon stem 

 or gynophore, showing the included ovum, a, and the radical canals, b. C, 2>, 

 female gonophores enlarged ; a, serminal vesicle ; b. vitellus; c, radial canals of 

 the imperfect nectocalyx ; d, canals of the manubrial cavity. E, male gonophore. 



and gynophores). Each female gonophore contains only a 

 single ovum, which projects into the cavity of the imperfectly 



