470. General Notes. [May, 
the one ovoid, as it were, isolated in the mucus and formed of 
glandular cells similar to those which enter into the structure of 
the epidermis,*the other fusiform and with filaments at their ex- 
tremity. The papille are joined to the body by long and slender 
a peduncles, —— F. E. Beddard (Ann. and Mag. Nat. Hist., Feb., 
_ 1886) describes three species of Perichæta and one of Moniligas- 
ter from Ceylon and the Philippines. The latter genus is remark- 
able for the apparent absence of a clitellum and the presence of 
five distinct gizzards in the cesophagus. 
Protozoa.—A, C. Stokes (Aun. and Mag. Nat. Hist.) describes 
several New Infusoria from American fresh waters. H. J. Car- 
ter describes in the January and February numbers of the Ann. 
and Mag. of Nat. Hist., thirty-five species of sponges from the 
neighborhood of Port Phillip heads, South Australia. 
aL EMBRYOLOGY. 
ON THE SYMMETRY OF THE FIRST SEGMENTATION FuRROWS OF 
‘THE Biasropisk oF ELASMOBRANCHII.—The nearly symmetrical 
subdivision of the blastodisk of Teleosts by the first four seg- 
mentation furrows has long been known. The details of the 
es carefully elaborated by Agassiz and Whitman,’ whose conclu- 
some sions are, I believe, generally accepted by embryologists. Of the 
X development of the blastodisk of Elasmobranchs we know com- 
paratively little, especially in relation to the relative lee and 
=~ direction of the first segmentation furrows. The object of the 
S present note will therefore be to describe the early segmentation 
of the blastodisk of one of the latter, viz., Rata erinacea, as dis- 
played by an egg removed from the oviduct and cloaca of a 
_ female of that species, July 11, 1885, at Wood’s Holl, Mass. , 
Upon opening the tough horny membranous envelope in which 
the ovum proper of Raia is enclosed; it is found that the egg § 
somewhat pinkish in color, and is imbedded in a layer of very 
- glairy “ white ” or albumen, which fills up the space between the 
egg and the horny case. The pinkish egg proper is somewhat 
flattened and oval in shape, and is immediately invested by a very 
thin and delicate vitelline membrane. At one side of the flattened 
vitellus, which measures nearly one and a quarter inches through 
its longest diameter, a small circular whitish area about two mit- 
_ limeters in diameter is noticeable. This is the blastodisk or get 
minal area of authors, and is the point where development first 
egins to manifest itself. d 
= H the egg case is carefully opened, the white removed an 
_ then laid into a one per cent solution of chromic acid, the blasto- 
_ 1Edited by JoHN A. Ryper, Smithsonian Institution, Washington, D. C. i 
___ žOn the development of some pelagic fish-eggs. Proc. Am, Acad. Arts and Sch 
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