4M REVIEWS. 
The larve are elongated oval, with six long legs and four ocelli. They 
Swarm over the gills of the mussel they are iiving on for a short time, 
and then bore into the substance of the gill to undergo their next trans- 
as in the first larval stage. The limbs are short and much larger than be- 
fore, the whole animal assuming an embryo-like appearance, and moving 
t like a rounded mass in its enclosure. Indeed is this process not 
viande Claparéde does not say so) a histolysis of the former larval tis- 
8 th 
the second larval round mass. Soon the body is artip and the pupa, 
as we may properly call it, slips out i: the larval mem 
and looks like an embryo just before hatching, but still lying within t 
egg. This may also be comparable with the formation of the adult " 
within the puparium. (Compare Weismann's account of this process in 
Musca, in our *‘ Guide to the Study of Insects," pp. 63, 64.) This period 
seems to be an exact repetition of the histolysis, and the formation of 
new tissues for the building up of a new body, which verni the pupal 
vil while the adult mite slips out s. its pupal membrane, just as the 
pupal mite throws off its larval errare like an adult butterfly, or 
fly, Viger d from its pupal membran 
mites, at least several jest pass through a series of meta- 
eoe similar to those of such insects as have a complete metamor- 
i 
osis in the spiders, is paralleled by the incomplete metamor- 
phosis of the orthoptera = Aea neuroptera, which reach adult life by 
simple moultings of the s 
In the genus Myobia feni m not only a deutovum, besides the original 
egg, but also a tritovum-stage. The eggs of this mite are long, oval and 
conical at the posterior end. The embryo with the rudiments of onim is 
represented by risa 5 ed Plate 8. The little tubercles md and mz w 
sent the mandibles and maxillæ, while the three pairs of legs, pp "p^, 
bud out from the sitddie of live ipsc lc represents the head-plate. The 
maxille and mandibles e to form a beak (x, Fig. 6) and the 
three pairs of feet ( PP zd eed along the median line of the body. 
ne development of the embryo is now for a time arrested, and à 
2d peculiar tooth-like process (Fig. 7,d.) is developed. Claparède thinks that 
by means of this the anterior end of the egg-shell is cut off, and the em- 
ro protrudes through, when (as in Fig. 7) it is seen to be ot by 
Te the deutovum (dt), equivalent to that of Atax. The 







