1886, | Embryology. ; 301 
vitellus. In the later profile (Fig. 10) the germ-band shows the 
appendages of the embryo developed as follows : the antennz az, 
the mandibles wd, the maxillæ mr, the three pairs of legs, 7, 2 
and 3, the collophoral segment, 1, and the following abdominal 
segments up to vi. In the next stage, when it may be said that 
the embryo is already beginning to lengthen, as shown in Fig. 7, 
the ventral plate, with its appendages, is no longer convex when 
viewed laterally in profile, but becomes strongly concave or bent 
upon itself, and it then appears as if it had been shortened, the 
embryonic appendages being also much crowded together at their 
distal ends, as shown in Figs. 6 and 7, which represent the same 
stage viewed from in front and in profile. In the course of fur- 
ther development the embryo increases still more in length, as 
shown in Fig. 5, when it may be said that the definitive form of 
the parent animal begins to be obvious. By this time the limbs 
and antenne have become definitely segmented. During the 
earlier stages the limbs, antennz, collophore, etc., had the form 
of mere blunt, paired papilla, or of blunt, clavate, tentacle-like 
paired outgrowths from the lateral surfaces of the ventral plate or 
elongated germinal area, 
e changes which determine the appropriation of the yolk, or 
whether a dorsal organ is developed which takes part in this or 
not, as held by Korotneff in the case of Gryllotalpa, are points 
which have not been made out. This, as well as the manner in 
which the blastoderm is formed, can only be made out by means_ 
of sections. ee 
The eggs, as well as the adult animals, are not, readily wetted 
with water or even in.dilute alcohol. I have succeeded in har- a 
dening them by treating them first with weak alcohol and after- X 
wards placing them in dilute chromic acid or Müller’s fluid. 
The egg of this species, after the formation of the germinal 
plate, is invested by an inner covering, 7, and an outer one, a as 
shown in Figs. 8 and 10. By very careful manipulation under a 
compressor the outer one may be ruptured, when it will be dis- 
covered that the inner one is wrinkled in the most singularly 
symmetrical fashion, as represented in Fig. 8. Whether this sec- 
ond wrinkled covering is the serous envelope or amnion I am not 
certain. It may be that it is a cuticular chitinous secretion from 
the cells of the blastoderm, such as has been found by Kingsley" 
to invest the embryo of Limulus while yet in the egg. Inside 
the second egg-envelope, and between it and the ovum proper, 
ere is a very considerable perivitelline space, 7, developed. __ 
Imperfect as these notes are, I publish them, first, because the 
development of this form differs greatly in its external features — 
from that of Isotoma, described by Packard; secondly, because > 
the development of this type recapitulates very briefly the devel- 
! Notes on the embryology of Limulus. Quart. Journ, Mic. Sci., Oct., 1885. 
