248 Analytical Notices of Books. 
anus, in which the intestine, now occupying the entire cavity of the pro- 
cess terminates. At the same time the extremity of this caudal process 
is gradually bent forwards beneath the central part of the embryo, until it 
is brought nearly into contact with the labrum. The maxille now begin 
to shew themselves ; first, the three anterior pairs, nearly in contact with 
each other, but at some little distance behind the mandibles; and after- 
wards the fourth and fifth pairs, the former arising from the spot where 
the hinder part of the body is bent upon the fore part, the latter from the 
portion which is bent upwards. In a short time, however, the posterior 
maxille are brought, by a change in the relative position of the parts, into 
the same level with the anterior. As their growth proceeds, the latter 
increase much more slowly than the former, so that at the close of this 
period the fifth pair are four or five times as large as the first, and so on 
in proportion with regard to the intermediate ones. Their extremities, 
as in the antenne and mandibles, separate from the surface of the central 
piece, and gradually become lobed, the two anterior pairs having each 
two lobes, and the three posterior, three. A longitudinal sulcus and six 
transverse ones, the latter corresponding with the several pieces of the 
trophi, now become visible on the surface of the central piece. 
Very shortly after the appearance of the hindermost pair of maxille, 
the five pairs of true legs are produced in regular succession from before 
backwards, on that portion of the tail-like appendage, which is turned 
upwards. Each of these, in its early stage of developement, is exactly 
similar to the hindermost maxille. Soon afterwards there appears on the 
outer side of the base of each, a small process, the rudiment of the 
future branchiz. In their relative proportion, the legs increase inversely 
with respect to the maxille; the anterior being at the close of this period 
about four times as long as the posterior. The true tail also now becomes 
more clearly developed, and the rudiments of its foliaceous appendages 
are visible at its extremity. At the same time six transverse furrows, 
the indications of its future articulations, are seen on its under surface. 
The authour next proceeds to trace, with great minuteness, the forma- 
tion of the internal organs, regarding the lamina of the embryo from 
which the intestines are derived, and which lies in contact with the vitellus, 
as mucous membrane, while he treats the outer lamina from which the 
external organs take their origin, as serous membrane. First appear the 
