ANDREWS: ANNULUS VENTRALIS. 
449 
pleopods or swimmerets, where it swells up and forms an almost 
invisible mucus-like mass hanging down from the pleopods. Very 
soon the female bends the abdomen forward under the thorax and 
deliberately lies down upon her back. The abdomen with its 
caudal fan widely expanded, is stretched so far forward over the 
thorax as to cover the bases of all the thoracic legs. The mucus-like 
secretion now adheres to the thorax as well as to the abdomen and the 
space between the ventral sides of the thorax and abdomen is filled up 
by this clear secretion. On the sides, the extensions of the abdominal 
pleura nearly close in this space so that a chamber full of mucus is 
formed. As the oviducts open on the bases of the third pair of thoracic 
legs (text-figure A), the eggs may come out into this chamber, a chamber 
into which the sperm might also issue and a chamber containing all 
the pleopods to which, as is well known, the eggs are affixed soon after 
being laid. 
On several occasions the actual issue of eggs from the two oviducts 
was seen. They flowed out in two streams as semiliquid masses, each 
egg distorted by pressure, and seemed forced out by rhythmic con¬ 
tractions, as if of the oviduct or the ovary. The female lay in such a 
position that the ventral surface of the thorax was inclined posteriorly 
and the streams of eggs were led by gravity downward and posteriorly 
into the above chamber. The concave surface of the sternal plates 
of the fourth thoracic somite (text-figure A), tended to concentrate 
the eggs toward the annulus so that they flowed over and close to the 
annulus before passing posteriorly into the chamber as into the hollow 
of a hand. Many eggs imbedded in the mucus or glaire were seen to 
flow slowly over the annulus. 
If, as above maintained the sperm comes out of the suture of the 
annulus at the time of laying and spreads out over the surface of the 
annulus it must come into the mucous secretion. But attempts to find 
it in the mucus and upon the eggs failed. The mucus, however, was 
not coagulated by 85 degrees water followed by Perenyi’s liquid and 
was often easily washed off in preparations, but yet in some prepara¬ 
tions a residue of glaire was found on the annulus. Thus in one case 
less than twenty-four hours after laying, the annulus was covered by 
a thick layer of glaire and when fixed in cold Worcester’s liquid and 
sectioned after carmine stain there were remnants of a coagulum over 
the annulus and some sperms in this mass. 
As these sperms were expanded and no longer in the form they have 
