330 Miscellaneous. 
ova may be directly and closely surrounded by the zoosperms ; the 
first phases of fecundation commence immediately. 
The ova and spermatozoids can, without being placed im contact, 
preserve their vital properties in the water for several hours. Our 
best fecundations were obtained with elements which did not come 
together until two or three hours after their extraction from the 
genital g olands. 
We shall not describe the first phases of the development of the 
ova; but we think we must record a fact which, we believe, has 
not before been observed: the embryos of O. angulata begin to move 
from seven to twelve hours after fecundation, according to the 
temperature. At Verdon we obtained some in seven hours, the 
water having a temperature of 22°. Their mobility was exhibited 
in rotatory and gyratory movements. Sometimes they turn on the 
spot as on a pivot; at others they remove rapidly and shoot like a 
dart across the field of observation. ‘The shell is formed at about 
the sixth or seventh day after the impregnation. 
The artificial fecundation presents no difficulty of execution; it 
ends, four times out of five, in the formation of a mobile embryo, if 
the elements employed are good. With the Portuguese oyster the 
laying is effected gradually, and sometimes lasts several weeks. 
When a speck in the genital gland becomes transparent, it is be- 
cause the elements are ripe; and itis then that they can be employed 
with advantage. 
In consequence of the preceding, and secing the fecundity of the 
oyster of the Tagus*, we tried some practical applications. For 
this purpose we prepared at Verdon a “clear” of 100 square 
metres surface, into which we poured the animated products of 
various artificial fecundations. The difficulty was to preserve the 
embryos while at the same time securing the renewal of the water. 
We attained that result by making the water enter and flow away 
through a bed of fine sand. 
After a month of reiterated experiments our endeavours were 
crowned with success. We had the satisfaction of finding some 
brood fixed on each of the tiles placed in our experimental “clear.” 
This is so much the more remarkable as, until last week, none had 
yet attached themselves to the numerous collectors immersed on the 
oyster-beds of the Gironde—that is to say in the very centre of the 
“ clear.” Comptes Rendus de 0 Académie des Sciences, July 31, 
1882, t. xcv. pp. 206-259. 
On a Synthetic Type of Annelid (Anoplonereis Herrmanni) a 
Commensal of Balanoglossus. By M. A. Grarp. 
The rich sandy beaches of the Iles Glénans, especially those of 
* 1 cubic centim. of ovary contains - Ova. 
By, dissociations is, Ween se. ss... 2500000 
IBYiSGethONSta te seasnste sake ¢ Sed 5200000 
Mica saga wate s «fate cucak 3850000 
The volume of the ovary of an oyster of average size varies between 6 
and 8 cubic centim. 
