448 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



into, minute, oblong, ciliated larvae ; these soon become attached by one 

 end and grow up into broad-disked young, like hydroids with long, 

 slender tentacle's ; each of these after a time sends out stolon-like tubes 

 from the base, and from these tubes buds are developed, each of which 

 grows up into a " scyphostoma/ 7 or hydroid-form, like the first one ; all 

 these eventually become much elongated, then circular constrictions begin 

 to form along the body, which grow deeper and deeper until they sepa- 

 rate the body into a series of concave segments, which are held together 

 by a pedicle in the middle of each, their borders at the same time be- 

 coming divided into eight lobes, or four bilobed ones ; in the mean time 

 the long tentacles around the upper end or original disk of the " scyph- 

 ostoma" gradually grow shorter and are finally entirely absorbed; then 

 the first or upper disk breaks off, and finally all the rest, one after 

 another, until a mere stump is left at the base ; after becoming detached 

 each of the disks swims about in the water, and gradually develops its 

 mouth, stomach, tentacles, and other organs, and, turning right side up 

 and rapidly growing larger, eventually becomes a large and complicated 

 jelly-fish, like its grandparents or great-grandparents that produced 

 the egg from which the original " scyphostoma " was developed. The 

 stump of the hydroid produces another set of tentacles, even before the 

 separation of all the segments, and grows up again iuto the elongated 

 or " strobila" form, and again undergoes the same process of transverse 

 division, thus producing successive crops of jelly-fishes. In these cases 

 there are alternations of generations, accompanied both by budding and 

 fissiparity. The young of this species in the "ephyra" stage were found 

 April 17, and at several other times during April, in abundance, by 

 Mr. Vinal N. Edwards. These were less than a quarter of an inch in 

 diameter, and must have become free only a short time before. On 

 April 30 he took young specimens from half an inch to about an inch 

 in diameter. The young of various sizes, up to nearly three inches in 

 diameter, were common at New Haven May 5. All these young speci- 

 mens were taken in the day-time. 



In some jelly-fishes buds may even be produced upon the proboscis of 

 the adult jelly-fish, which develop directly into free jelly-fishes, like the 

 parent. This is the case with the Dysmorphosa fulgurans, found in these 

 waters, and with Lizzla grata, found farther north. 



On the other hand there are many jelly-fishes that do not have a 

 hydroid state, nor bud, nor pass through any marked metamorphosis. 

 This is the case with our Pleurobrachia rhododactyla, Idyia roseola, and 

 other Ctenophorse. In these the young, even before hatching, become 

 perfect little jelly-fishes, and swim round and round within the egg by 

 means of the miniature paddles or flappers along their sides. The young 

 are, nevertheless, very different from the adults in form and structure. 



It will be apparent, from the preceding remarks, that a complete 

 list of free-swimming animals would necessarily include all the Aca- 

 lephs of the region, but, as this would uselessly swell the list, only 



