66 Miscellaneous. 
examination by means of sections. My observations are therefore 
very meagre and inadequate, especially as regards the organogeny 
of the form, owing to the extreme scarcity of the larvee. These im- 
portant deficiencies I hope subsequently to supply when I shall have 
been able to examine my material by sectional methods. The 
general appearance of the Hampton form presents many points of 
slight divergence from the species common at Naples (B. minutus), 
so that at first sight the two animals seem very different; but 
whether the anatomy of this form is essentially different, I could 
not decide by examination of fresh specimens alone. The principal 
result of my work has been to show that the form common on the 
Chesapeake coast does not pass through the Tornaria stage, which 
has been described by previous observers as the larva of Balanoglossus, 
The eggs of this animal are opaque, yellowish-grey bodies, enclosed 
in a thin tough egg-shell which is quite transparent. Segmentation 
is begun by the appearance of a median furrow which divides the 
ege into two equal halves. This is followed by another median 
furrow at right angles to the first, forming four segments. In the 
next stage that I have been able to observe segmentation was com- 
plete, having probably proceeded in a regular manner, though 
this I have not been able to determine. One edge of the blasto- 
derm is next flattened and gradually depressed, causing the embryo 
to take the shape of a concavo-convex disk. The concavity be- 
comes gradually reduced in size as its edges grow together to form 
the blastopore, appearing at the same time to become thickened. 
This process is continued until the blastopore becomes exceedingly 
small; whether it subsequently disappears or not I cannot say until 
I have cut sections of it. I believe, however, that it becomes the 
anus, which at all events is found in the same position. As this 
gastrula becomes shut off it resumes the spherical shape and begins 
to rotate about the axis which eventually becomes the long axis of 
the animal, at the top of which the blastopore is placed. This 
rotatory movement is caused by a uniform covering of fine cilia, 
After rotating in this way for some few hours, the body elongates 
and aring of large cilia appears surrounding the posterior end. 
The animal then swims round the egg, rotating at the same time on 
its long axis. A nearly median transverse constriction next occurs, 
which is followed by another one anterior to it, giving the body the 
appearance of being composed of three segments. The anterior seg- 
ment becomes the proboscis, the middle one forms the collar, and 
from the posterior portion the rest of the body is developed. With- 
in the anterior constriction the mouth is subsequently formed. At 
the anterior end of the proboscis a tuft of fine long cilia grows 
out as in the larvee of many Cheetopoda, &c. A pair of depressions 
are at the same time formed posteriorly to the collar in a dorsal 
position. These depressions form the first pair of gill-slits. In 
this condition the larva is generally hatched, though I have found 
individuals already free before the appearance of the transverse con- 
striction. On hatching these larve are still quite opaque, and live 
buried in the muddy sand which the adults inhabit. In this con- 
