Royal Physical Society. 63 



V. On the Reproduction of Cydippe pomiformis. By T. Strethill 

 Wright, M.D., Fellow of the Royal College of Physicians, Edinburgh. 



Accounts of Cydippe may be found in every manual of 

 Natural History and Comparative Anatomy. Those written 

 by British authors are generally distinguished by a singular 

 variety in error both of description and illustration. I have, 

 therefore, thought it necessary to give to the Society a sketch 

 of its anatomical structure, as maintained chiefly by Agassiz 

 in his admirable work on the Acalephse of North America, and 

 which my own observations assure me is correct. 



Cydippe (see fig. 1) may be briefly Fi g- i- 



described as a transparent ovoid r x ^^wi''"^ 



body of gelatinous consistence, hav- ^^Ss II IPv^C 



ing its surface longitudinally sul- 13 a I tJtv\ 



cated (like that of a melon) by / itMll i| -3 It) 



eight furrows, in each of which lies 1 \ f) 



a band of muscular tissue. These € < \ \ ( pMt 



muscular bands serve as a basis of -1 %m 



attachment to numerous flat paddles ^ 1J 



or comb-shaped fringes of cilia, |k I 



which are ranged at nearly equal jfi ^ 



distances along the whole length of a. Mouth opening into stomach, 



the bands, and form a locomotive 7^ h comm ™\™^ at d with 



m ob large central canal of water- 



apparatus by which the animal rows vascular system. c ccc Longi- 

 itself through the water with admir- tn^f^ZZ^ T** Carry ^ g 



o xx ciliary paddles, and covering the 



able swiftness and grace. In the lateral water-vascular canals, e e 



„iT„ i „„ i -i TT) A1 • , Transverse water-vascular canr Is. 



allied acalephs, Beroe, Alcinoe, and /Receptacle of the tentacles <,. 



Bolina, each of these paddles is a transparent plate, more or less 

 divided or fringed only at its extremity, while in Cydippe the 

 plate is entirely divided to its attachment into a fringe of sepa- 

 rate cilia. Agassiz considers that the cilia are composed of a 

 peculiar substance, but I find that their action on polarized 

 light is proportionate to that exerted by a plate of horn of 

 equal thickness. The cilia are, therefore, in all probability, 

 setae and their embryonic development, hereafter described, 

 indicates that they are analogous to the locomotive setae of the 



