1879.] 829 [Scudder. 
6. The mouth is formed as an invagination of the ectoderm, 
directly opposite the region where the blastopore was situated at an 
earlier stage. 
7. ‘The anus makes its appearance soon after, close to the mouth, 
and therefore nearly opposite the position of the blastopore. The in- 
testine appears to be formed by an outgrowth from the digestive tract. 
The pulmonate and the lamellibranch are thus seen to resemble 
each other in having the blastopore converted into the shell area, 
and the mouth formed nearly opposite by an invagination of the 
ectoderm. 
In both groups the anus is distinct from the blastopore, and is 
formed after the obliteration of the latter and the formation of the 
mouth, but the invagination neck of the pulmonate migrates from its 
primitive position to the new anus, and becomes converted into the 
intestine, while the intestine of the oyster appears to have no relation 
whatever with the invagination neck. 
The critical discussion of these facts and the comparison of them 
with other published observations will be undertaken in another place 
after the figures of the various stages have been published. 
Mr, S. H. Scudder offered a few suggestions concerning 
the probable age of Haulover Beach at the head of Nantucket 
Harbor. 
The conformation of the northeastern part of Nantucket is very 
peculiar, the easterly extension of the harbor being separated from the 
ocean by only a narrow strip of land on the north, and by a still 
narrower one on the east. So low and so narrow is this strip next 
the upper extremity of the harbor, that by digging a short and shal- 
low trench through the sand dunes, the fishermen have constructed a 
very easy “ haulover ” for their boats. The question of opening this 
narrow neck of land to the free passage of the sea has been mooted by 
officers of the U. S. Coast Survey ; this, they say, is both perfectly 
feasible, and could be done at a comparatively small expense. It is 
believed that by means of tidal currents which would naturally flow 
through such an opening, the channels in the present difficult 
approaches to Nantucket Harbor would be deepened and broad- 
ened. Whether this result would follow and the Haulover beach 
remain permanently open would depend in large measure upon 
whether this neck of land is as old as the rest of the island or amore 
