Miscellaneous. 79 
fourth pair that they possess on issuing from the egg. When the 
males haye the fourth pair of legs disproportionately large, these legs 
remain small throughout the preparatory state, and only acquire their 
large size under the skin of the nympha before the last moult. The 
larvee undergo from two to three moults before passing to the state 
of nymph. ‘They have only one pair of hairs at the apex of the 
abdomen. 
The Nymphe.—tThe impuberal octopod individuals, or nymphe, 
show no distinctive sexual characters. In those species the males 
of which have the fourth pair of legs disproportionately large, these 
remain small during the whole of this state, and increase in size 
under the skin before the last moult, at the same time that the 
sexual organs are produced. At the same period are formed the 
posterior prolongations of the abdomen in some species; and at its 
close the sex of the individuals may be distinguished. 
In the larva from which a nympha is to be produced, the fourth 
pair of feet are seen beneath the skin, folded forwards. These and 
the lobes and hairs borne by many nymphe are evidently produced 
beneath the skin of the larva. The nymphe have two pairs of long 
setze at the apex of the abdomen. 
The nymphe have only the single granular tequmentary plate of the 
epistoma, the thoraco-abdominal plate of the sexual individuals being 
wanting in them. They undergo two or three moults in this state. 
The coupled females.—These, although larger, are not always easy 
to distinguish from the nymph ; in some species they have two 
colourless appendages to the hinder part of the body, which do not 
exist in the nymphe. This copulation of adult males with indi- 
viduals haying no sexual organs is remarkable, as nothing of the 
kind has been observed in T'yroglyphus, Glyciphaqus, &c., although 
a similar phenomenon was noticed in Psoroptes by Bourguignon and 
Delafond. In these ayicolar Sarcoptide a female may often be seen 
in copulation and retained by the male, showing through her integu- 
ments a female with well-developed genital organs. The adhesion 
of the male to the female is effected by means of the two anal disks 
possessed by the former. The adhesion lasts for some days, but the 
actual eoition seems to occupy but a small portion of this time. The 
ova are developed in the ovaries of the females whilst still in this 
nymph-like form, and before the final moult. 
The author remarks upon the relationships of these parasitic Sar- 
coptidee, and gives the following list, in a note, of the forms observed 
by him, which will be fully described in his memoir :—1. Ptero- 
lichus, g.n., including 5 new species; 2. Dermalichus (Koch), sp. 
passerinus (Linn.), oseinum (Koch), and 1 new species; 3. Ptero- 
nyssus, g.n., sp. Dermal. picinus (Koch); 4. Proctophyllodes, g. n., 
sp. Dermal. glandarinus (Koch), and 4 new species ; 5. Pterodectes, 
g.n., with 3 new species.—Comptes Rendus, tome lxvi. April 20, 
1868, pp. 776-786. 
The Pelvis and Hind Limbs of Whales. 
Professor Yan Beneden has read a paper at the Academy of 
