IN LAPHNIA, AND OF THE STETJCTURE OF THE EPHIPPITJM. 
95 
his observations, and on the other hand, of course, to throw more doubt on the entirely 
different accounts of J, V. Caeus and Dr. Buknett. I must, however, confess, that like 
the two last-mentioned observers, I have been quite unable to detect any germinal vesicle 
in the eggs of the viviparous Aphides ; it is, however, very difficult to find even in those 
eggs which are destined to be impregnated in the ordinary manner, or indeed in any 
insect eggs, while, on the contrary, I have found it to be very large in all the eggs of 
Crustacea which have come under my notice. 
Parthenogenesis in the Articulata. 
From the hardness of the outer skin, and from the finality in the mode of growth, 
parthenogenesis in the Articulata is effected by means of bodies in theh origin and 
structui’e very similar to true eggs. 
The Crustacea are so seldom bred and watched in captivity, that though the Daphniadse 
is the only family in the class which is as yet known to reproduce by parthenogenesis, 
yet the instances may hereafter prove to be much more frequent, as the fact that no 
males have yet been found of Toly])hemus oculus, Lininadia gigas or Apus would seem to 
suggest. 
Similar phenomena have been recorded by Dumeeil*, and more recently by Newman f. 
In the Insects, excepting the celebrated case of the Aphides and the genera Cynips 
and Apophylliis, as stated by Haetig;];;, whose assertions have been confirmed by the 
appearance of Cynips lignicola in great numbers in the south-west of England within 
the last year or two, where in several thousand specimens not a male occurred ; — with 
these exceptions, I say, the phenomenon of parthenogenesis has as yet only been met 
with in the Lepidoptera, probably because this is the order most frequently bred by 
collectors. 
Pallas has obseiwed this phenomenon in Puprepia casta ; Beenoulli in Gastrophaga 
potatoria and Episenia caernleocephala ; Baslee in G. guerdfolia ; Suckow in G. pini ; 
Teevieanus in Sphinx ligustri, and Noedmann vnSmerinthus popnli. These instances are 
mentioned in Buemeistee’s Manual, p. 312 ; and Siebold § has attempted to explain them 
away, but in the present state of our knowledge the assertions are more probable than the 
explanation. 
Moreover, vSiebold himself has observed parthenogenesis in Solenolia Uchenella and 
S. clathrella |1, in Psyche helix and in Agns^. 
Lacoedaiee** mentions the same fact as having occurred in Liparis dispar for three 
successive generations. 
* Academie des Sciences, 28th Sept. 1856. 
t An Essay on the employment of Physiological Characters in the Classification of Animals. 
t Geemae’s Zeitschrift, vol. ii. p. 178. 
§ Wahre Parthenogenesis hei Schmetterlinge, &c. 
II Bemerk. fiber Psychiden ; -Jahreshericht der Schlesischen GeseUschaft, &c., 1850 ; translated also in 
the Transactions of the Entomological Society of London, N. S. vol. vi. 
^ AVahre Parthenogenesis, &c. ** Introd. to Ent. vol. ii. p.383. 
