LEUCKART, ON DEVELOPMENT OF ECHINORHYNCHUS, 57 
with the neck retracted, and having the sexual organs unde- 
veloped. From all appearance these were waiting to be 
transferred to the intestine of a higher animal, and from the 
construction of their proboscis the suspicion was awakened 
that they might be derived from Kchinorhynchus Proteus. 
Induced by these circumstances I selected Gammarus Pulex 
as the subject of my researches. Having placed abundance 
of these crustaceans in a vessel of water, I introduced into it 
the ova afforded from six or eight female Echinorhynchi, and 
in the course of a few days had the satisfaction of detecting 
not only numerous ova in the intestinal canal of the Gammari, 
but also of seeing that the embyros had quitted the egg-shell, 
and had made their way through the walls of the intestine 
into the visceral cavity, whence they had wandered in various 
directions into the appendages, and had begun to grow. In 
a short time I was thus convinced, that in Gammarus pulex 
I had discovered the true intermediate supporter of the 
entozoon. 
The ova of Echinorhynchus Proteus, in form and structure, 
resemble those of the allied species. They are of a fusiform 
shape, and surrounded with two membranes, an external, 
of a more albuminous nature, and an znternal, chitinous. 
When the eggs have reached the intestine, the outer of 
these membranes is lost, being mm fact digested, whilst the 
inner envelope remains until ruptured by the embryo, usually 
in the middle. 
The embryo when it quits the egg measures 0°056 mm. in 
length, and 0:014mm. in thickness. The hinder extremity 
is attenuated and pointed, the anterior truncated obliquely 
towards the ventral aspect. The surface thus formed, and which 
may be termed the vertex, supports a bilateral apparatus of 
spines. I counted five (rarely six) spines, which are inserted, 
at a certain distance on each side of the median line, in an ex- 
anded arch; so that the central spine, which is also the longest 
of all (0002 mm.), occupies the highest position. Neither 
root nor claw can be distinguished in these spines. They 
present the appearance of straight ridges closely applied to 
the cuticle, and project only at the extremity in the form of 
a blunt pomt. Between the two halves of this apparatus of 
spines may be seen, close to the median line, on each side, 
also another short chitinous elevation or ridge, which consti- 
tutes with the above described spines, a more or less perfect 
right angle. G. Wagener regards these ridges as a pair of 
lips, between which is placed a slit-like pone, but in reality 
they are merely thickenings of the cuticle, which afford a firm 
point of insertion for the contractile substance of the embryo, 
