ZOOLOGY. Q47 
non-existence, as compared with its presence in evidence of its existence. 
Nevertheless, its absence in so many specimens as Dr. Seeley has had the 
opportunity of examining renders it necessary to ascertain whether the 
element in question is a dismemberment of some other bone or not. And 
this I must leave to those who have more extended material for examina- 
tion. Dr. Seeley’s objections to my determination of the frontals (? nasals) 
are not weighty, and are anticipated in the memoir itself. 
On the whole, the probabilities of the Cuvierian nomenclature of the 
bones of the cranial roof being correct is rather increased by Dr. Seeley’s 
remarks, but Ihave not been able to discover that any one has correctly 
determined the squamosal, quadratojugal, opisthotic, and stapedial bones 
before the reading of my paper. 
2. On THe Emsryotocy or Limutus Potypuemus. By A.S. 
Pacxarp, Jr., of Salem, Mass. 
(Abstract.) 
Tue eggs on which the following observations were made were 
kindly sent me from New Jersey, by Rev. Samuel Lockwood, who 
has given an account of the mode of spawning, and other habits, 
inthe “ American Naturalist.” They were laid on the 16th of May, 
but it was not until June 3d that I was able to study them. The 
eggs measure .07 of an inch in diameter, and are green. In the © 
ovary they are of various hues of pink and green just previous to 
being laid, the smaller ones being, as usual, white. The eggs are 
.simple, the ovarian eggs being formed of a single cell. The yolk 
is dense, homogeneous, and the yolk granules, or cells, are very 
small, and only in certain specimens, owing to the thickness and 
opacity of the egg-shell, could they be detected. 
Not only in the eggs already laid, but in unfertilized ones taken 
from the ovary the yolk had shrunken slightly, leaving a clear 
space between it and the shell. Only one or two eggs were ob- 
served in process of segmentation. In one the yolk was subdi- 
vided into three masses of unequal size. In another the process 
of subdivision had become nearly completed. 
In the rlext stage observed, the first indications of the embryo 
consisted of three minute, flattened, rounded tubercles, the two 
anterior placed side by side, with the third immediately behind 
“them. The pair of tubercles probably represent the first pair of 
limbs, and the third, single tubercle the abdomen. Seen in out- 
e 
