318 History of British Entomostraca. 
wards bear, (Fig. 12.) At each moulting the number of segments into 
which the body and tail are divided increase in number ; the num- 
ber of articulations and the length of antennae increase, &c., but it 
is not till after the third moulting that the insect is perfect and ca- 
pable of producing its species.* 
A question has been started whether the Cyclops should be con- 
sidered oviparous or viviparous insects ; and it appears to be one 
of some difficulty, as they would seem from what I have stated to 
be both. Geoffroy states that all the Monoculi are oviparous.t De 
Geer also says they are oviparous. " However," he immediately 
adds, " as the Monoculi never quit their eggs before the young ones 
are hatched, we may perhaps regard them as viviparous/'^ Jurine 
says it is difficult to decide. Viviparous young, he says, increase in 
size every day, and have constant need of a mother's care if she 
die, all die. As, however, the young of the Cyclops do not increase 
in size after passing from the internal ovary, and as, from numerous 
experiments which he details, they were found, after having passed 
into the external ovary, to be independent of the life of the mother, 
even if she were killed by spirits of wine they must, he concludes, 
be considered oviparous. 
The process of moulting, under which the little creature frequent- 
ly succumbs, is both interesting and curious. The new shell or 
* The recent alleged discoveries of Mr Thompson, of the metamorphoses which 
the young of several genera of the Cirrhipedes and Crustacea undergo, have ex- 
cited a good deal of attention of late to this very interesting subject. Accord- 
ing to Mr Thompson, the genus Zoea of Bosc, which figures away in many of 
our arrangements, as one of our Entomostraca, is nothing more nor less than the 
larva of the common crab, in its first state. ( Vide Zoological Researches, No. 
I. and succeeding. ) M. Burmeister has verified Mr Thompson's discoveries with 
regard to the metamorphoses which the Cirrhipedes undergo ; but many doubts 
still continue to be thrown upon his observations with regard to the genera of 
Crustacea. One or two genera of each of the great groups of the Malacostraca 
have been apparently satisfactorily ascertained to undergo no metamorphosis and 
the labours of M. Rathke, with the observations of other writers, and especially of 
Mr Westwood, in a paper published in the Philosophical Transactions for 1835, 
leave the matter still in doubt, and show the necessity of Mr Thompson's obser- 
vations being confirmed before this interesting question can be settled. The 
insects of the genus Cyclops approach so near to some of the Malacostraca, 
however, that were we to reason from analogy alone, we might easily conceive 
Mr Thompson's discoveries to be partly confirmed as the changes which they 
undergo are almost equally wonderful with any of the genera which he has made 
the subject of his observations. 
f Histoire abregee des Insectes, p. 654. 
\ Mem. pour servir a 1'hist. des Insectes, Vol. vii. p. 435. 
Hist, des Monoc. p. 17. 
