a new Geniis of Corynoid Polypes. 79 



In its movements and mode of life^ the sexual zooid of Clava- 

 tella presents a marked contrast to the Medusoid of other Hy- 

 drozoa. The latter is active and mercmial, dancing gaily through 

 the water by means of the vigorous strokes of its crystalline 

 calyx. The former strides leisurely along on its stilt- like legs, 

 or, using the adhesive disks as hands, climbs amongst the 

 branches of the weed. It is also much hardier, and can be kept 

 alive much longer in captivity than the Medusoids. I succeeded 

 in preserving one specimen for about three weeks. During a 

 considerable portion of this time, it led an active life, crawling 

 about on the sides of the vessel in which it was confined, or 

 climbing over the long green filaments of a tuft of sea-weed. 

 After a while, however, it became stationary, fixing itself to 

 some of the stems by means of its six sucking-disks ; and thus 

 it remained, the proximal portion of the body, with the six red 

 specks, being uppermost, and the capitate arms standing out 

 rigidly, like the rays of a star-fish. In this state, I imagine, it 

 continues until the embryos are matured and ready to escape. 

 All that I succeeded in keeping for any time passed into this 

 quiescent and rigid condition after a while, exhibiting little 

 subsequent change. 



Owing to the semi-opacity of the outer integument, it is ex- 

 tremely difficult to study the internal structure of the zooid, or 

 to detect the generative products. In one or two instances, 

 however, I was able to distinguish globular bodies (ova) in the 

 hinder portion of it ; and on one occasion I witnessed the move- 

 ments of an embryo within, which, in its struggles to escape, 

 caused a frequent distention of the oral surface, retreating appa- 

 rently after each attempt into the cavity of the body. My ob- 

 servations in this case were brought to an untimely end at the 

 most interesting point by the drying up of the water which 

 contained the zooid, and I was not fortunate enough to meet 

 with a similar opportunity again. 



'* On y distingue tres-clairement une espece de lentille hemispherique, 

 parfaitement transparente, dont la base est enveloppee d'une couche de 

 pigment a granulations tres-fines et d'un beau rouge carmin. En passant 

 par-dessus cette espece de cristallin, les tegumens acquierent une epaisseur 

 considerable et forraent une saillie bien marquee a la surface du corps; 

 mais la courbure de ces deux parties de I'appareil refringent n'est pas la 

 meme : I'exterieure doit necessairement agir comme lentille divergente, 

 I'interieure comme lentille convergente ; et comme elles sont erichainees 

 immediateraent I'une dans i'autre, il s'ensuit qu'elles sont disposees abso- 

 lument comme les deux elemens d'une lentille achromatique. La petitesse 

 des objets et le pen de transparence des parties m'ont empeche de recon- 

 naitre d'autres details ; mais ce que nous en avons distingue suffit, ce nous 

 semble, pour qu'il soit impossible de se refuser a voir dans I'organe que 

 nous de'crivons un appareil de vision — un veritable ceil." 



