REVIEWS. 49 
draws attention to the great differences in the formation of the 
egg and the germ of these parasites from what occurs in other 
insects. The egg has no nutritive cells; the formation of the 
primitive band, usually the first indication of the germ, is retarded 
till the second larval stage is attained; and the embryonal mem- 
brane is not homologous with the so-called ‘‘amnion” of other 
insects, but may possibly be compared witb the skin developed on 
the upper side of the germ of the low, worm-like acarian, Pen- 
tastomum, and the ‘larval skin” of the embryos of many low 
Crustacea. He says, also, that we cannot, perhaps, find the ho- 
mologues of the provisional organs of the larva, such as the 
singularly shaped an- 
tennz, the claw-like 
mandibles, the tongue- - 
or ear-like appendages, 
in other Arthropoda 
(insects and Crusta-- 
cea); but that they 
may be found in the 
parasitic Lernean crus- 
taceans, and in the 
leeches, such as His- 
triobdella. He is also 
struck by the similarity 
in the development of fi- 
these egg-parasites to IB; 
that of a kind of leech 
a ) ance Development of Egg-parasite. : F 
with ciliæ, recalling the larva of Teleas (Fig. B, C,), while in the 
true leeches (Hirudo) the primitive band is not developed until 
r they have passed through a provisional larval stage. 
This er metamorphosis of the nee peaniien; Ganin 
also compares to the so-called ‘‘ hyper-metamorphosis 
insects (Meloe, Sitaris, and the Stylopidz) made kaom by Sie 
bold, Newport and Fabre, and he considers it to be of the same 
nature. 
= 
Fig. 20. 
© 
0 
DOVOO GN 
DWOOOE 
= 
q 
Jinan id dibsivg eetipeses such early larval, fortes es these 
given in Figs. 17 and 19 to the free swimming Copepoda. Finally, 
he says a few words on the theory of evolution, and remarks 
AMER. NATURALIST, VOL. V. 4 
