76 Miscellaneous. 
the penetration of the spermatozoid, the vitellus loses its spherical 
form and becomes much flattened at one of its poles. At this pole 
a small layer of clear protoplasm collects, in the midst of which the 
first polar globule appears, soon followed by a second ; the vitellus 
resumes its original form ; and soon afterwards the segmentation of 
the ovum begins. Quatrefages says that the first segmentation- 
groove, which divides the ovum into two unequal spheres, makes. its 
appearance upon any part of the surface; but the author thinks 
that this is not the case, as he has always seen the first groove or 
plane of segmentation occur in the direction of the point where the 
polar globules had made their appearance, as observed by Halley 
and others in Leptoplax tremellaris. He thinks that the property 
of the polar globules of determining the direction of the first seg- 
mentation-groove is the only part of the function of those remark- 
able bodies of which we know with certainty, and that consequently 
they are well entitled to their old name of directive bodies. 
Quatrefages’s description of the segmentation of the ovum in 
Hermella is said by the author to be quite erroneous ; but the only 
details he gives are that the segmentation seems to have much ana- 
logy with that of the ovum of the Naiades (Flemming)* and of the 
common mussel (Théodore Barrois)t. The animal spheres finally 
surround the vegetative part of the ovum, and thus form an am- 
phiblastula. 
Twelve hours after impregnation the embryo has the form of a 
mesotrochal larva with a group of long cilia at its cephalic pole, 
besides its vibratile belt. The larva, when four days old, has a 
dome-like form, owing to the preoral part being strongly developed. 
The mouth opens into a long cesophagus lined with vibratile cilia, 
and separated by an annular constriction [from the intestine ?]. The 
latter opens by a terminal anus. On the ventral side a ciliary fur- 
row is directed towards the mouth. To the right and left of the 
intestine there is a bundle of four provisional sete. The dorsal 
surface of the preoral part has two small brown ocular patches. The 
larva differs in several respects from those of other sedentary anne- 
lids; the larva of Terebellides Streemii alone presents some points of 
analogy, according to the description of Willemoes-Suhm+.— Bulletin 
Scientifique du Département du Nord, 4° année, 1881, pp. 1-4. 
On the Condylarthra. 
Professor Cope made some observations on the characters of the 
newly-discovered group of Perissodactyle Ungulates which he had 
called the Condylarthra. He defined it as follows, comparing it 
with the typical Perissodactyla, which he referred to a suborder 
under the name Diplarthra. 
Astragalus with one uniformly convex distal articular 
face; humerus with epicondylar foramen .... Condylarthra. 
* Sitzungsb. d. Wien. Akad. Bd. lxxi. 
+ Bull. Sci. du dép. du Nord, 1879. 
t Versl. en Meded. Kon, Akad. Amsterdam. 
