LOT 
length. The abdomen only lengthens a very little. The 
elongation takes place during the development of the 
horns and before the eyes and the other organs disappear. 
This condition is shown on Plate LV., fig. 6; the nat. 
size is ll’"4 mm. The next phase, represented on Plate 
IV ., fig. 7. shows that the development of the horns, the 
disappearance of various. appendages, and the great 
lengthening of the genital segment is followed by a loop- 
ing of the posterior region of the latter. This loop 
eradually expands, and finally takes on the adult 
condition. 
In the metamorphosis of the cephalo-thorax the ovaries 
are thrust into the genital segment, and take up a position 
on the dorsal aspect of the posterior region of that seg- 
ment, in such a manner that the more anteriorly placed 
portion of the ovary in the adult is what was the posterior 
part in the cyclops stage (see Plate V., figs. 1 and 4). 
The cyclops stage of Lernea was first found in setu by 
a8 
Metzger,* who published a short note on the observations 
made and the conclusions arrived at early in 1868. 
Claust later on in the same year, from specimens supplied 
by Metzger and fresh material, confirmed the observations 
of that Zoologist. 
ConcLUDING REMARKS. 
In the account set forth on the above pages, it will be 
seen that there are remarkable differences between the 
changes that take place in the hfe history of the two cope- 
pods before they reach maturity. In the one case 
(Lepeophtheirus) the lite history exhibits a series of pro- 
gressive developments. In the other (Lernwa), although 
* Ueber das Mannchen u. Weibchen der Gattung Lernaa, vor dem 
Hintritt der sog. riickschreitenden Metamorphose. Jany., 1868. 
+ Beobachtungen ueber Leriwocera, Peniculus, und Lernea, 1868. 
