MR. R. OWEN ON THE ANATOMY OF THE CALYPTRAID&, 209 
the female, and the ¢estis in the male, suddenly turns upon itself, passes dorsad of the 
stomach, adhering to the roof of the branchial chamber, and terminates by a small 
projecting anus on the right side of the orifice of the branchial chamber, anterior to 
the renal, or mucous, gland. 
In the male! the testis occupies the apex of the triangular visceral mass which is 
lodged between the internal and external shelly plates ; it surrounds the fold of the in- 
testine, and gives off the vas deferens near the pylorus. The excretory duct passes dorsad 
of the rectum and stomach, inclines dextrad, and runs along a groove to the outer side 
of the base of the penis, which it there penetrates: its disposition within the intro- 
mittent organ I have not been able to determine satisfactorily. 
The ovarium in the female occupies a corresponding situation to the ¢estis in the male, 
and, like it, is in close contact with the concave side of the branchial chamber. It is 
of considerable size in the large specimens, forming the principal mass of the viscera. 
The oviduct in these specimens projects a little from the mantle : it terminates posterior 
to the anus, as above described. A mucous gland, probably analogous to a renal organ, 
is lodged in a membranous chamber, about 3 lines in length and 2 in breadth, close to 
the termination of the rectum, at the entrance of the branchial chamber. It consists of 
a glandular part, of a light brown colour, and fibrous texture when seen under the lens; 
though from analogy the apparent fibres are no doubt secreting tubes. By the side of 
this gland there is a bag appropriated to receive the secretion, which bag or dilated 
duct communicates with the termination of the oviduct in the female, in which sex 
this gland is larger than in the male. 
. The heart is readily distinguishable, by the colour of the ventricle, through the trans- 
parent pericardium, which is situated on the left side of the stomach. The branchial 
vein receives the blood from the branchial filaments by a vessel which runs along the 
dorsal aspect of the base of the filaments, a little above their inserted extremities : three 
or four veins from this marginal vessel anastomose upon the roof of the branchial cham- 
ber, and communicate by a common trunk with the auricle. The veins of the body run 
over the floor of the branchial chamber, and terminate in a marginal vessel which runs 
parallel with the inserted extremities of the branchial filaments. From this vessel, a 
small branch is given off to each filament, which, under the microscope, may be seen 
to turn over the free extremity of the central horny support, and passing down the op- 
posite side, to enter the branchial vein. This is analogous to the structure of the tem- 
' My first dissections were of female specimens of Calyptrea, as all that I then possessed were of that sex; 
but since the reading of this Paper I have met with a male Calypeopsis in the collection made by Capt. P. P. 
King, and have been favoured with a second male specimen of Calyptrea by the kindness of J. E, Gray, Esq., 
from which specimens the above account of the male organs is derived. 
