98 ZOOPHYTES. 



It is from nascent animals that the structure can be most satisfactorily 

 ascertained. But while floating reversed, that is, with the hydra down- 

 wards, they have a horizontal rotation, probably from the action of the 

 tentacula or cilia below ; sometimes exceedingly inconvenient to the obser- 

 ver in shifting the objects from the focus, or from the field of the micro- 

 scope. 



A single hydra is developed in the ovum, but a companion to this 

 original animal is generated from the same base, within thirty hours of its 

 production ; and a third then rises between the two. At this stage the 

 product is light greenish-yellow. One basis having thus generated six 

 nascent hydrse, had become circular ; and here the evolution of three 

 ensued in eight days. Such evolution is apparently successive. — PI. XXVII. 

 fig. 13. From the object represented, a figure, which appears in most 

 works treating of the Lunate Zoophytes, may be understood, but which I 

 could never previously comprehend. In that figure are shewn four ani- 

 mals which are originating Cristatelloc. It was given first by Rosel, who 

 represents several of the young Cristatellae soon after their liberation 

 from the ovum, but he gives no figure of the parent. — Tom. iii. Plate xci. 



Unfortunately it is impossible to preserve the animals thus bred from 

 the ovum until acquiring their oval shape. 



The great breeding season occupies April and May. It continued 

 throughout the month of June in the year 1838. 



The ova of the fine subject above described, first began to open for 

 production of the young in 202 days after the hydrse ceased to protrude 

 from the mass, and the latest period of opening was 230 days after the 

 same cessation. 



The specimen, Plate XXVIII. fig. 6, was procured on the 3d of Octo- 

 ber, when it seemed quite replete with ova, irregularly disposed, whereof 

 about 24 could be enumerated. Their dark sides and yellow circum- 

 ference, were agreeably contrasted with the translucent green of the Crista- 

 tella. As its flesh decayed, 33 had escaped on the 3d of December, that 

 is, in sixty days, each now floating with the gelatinous matter investing it. 



In some specimens, a number of dark opaque corpuscula, denoting im- 

 mature ova, may be seen near the root of the hydrse, apparently between 



