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for a long distance and thereafter the arteria hepatica ; it receives the duct from 

 the gall-hhidder, then that from the right lobe of the liver and — still accompanied 

 by the A. hepatica — enters into the alimentary canal on the ventral side at the 

 spot indicated above. 



The heart (c) lies remarkably far from the ventral margin, high up between 

 the clavicles, with the longitudinal axis placed ol)liquely so that the bulbus of the 

 branchial artery points downwards and forwards. The aorta (ao) lies to the right 

 of the middle line of the vertebral centra, accompanied by a large right cardinal 

 vein and a thin left cardinal (cp). Close behind the head the aorta gives off to 

 each side — a little asymmetrically -— a large artery to the muscles of the pectoral 

 fins {ap), and almost at the same place though more ventrally and to the right 

 the large Arteria cœliaca. This runs along the right side of the œsophagus-stomach, 

 with branches to this, then further under the swim-bladder; under the middle of 

 this it gives off a fairly large branch to the "red body" {rete mirahile) on the under 

 side and divides into 2 branches, one to each of the two windings of the intestine 

 following the latter and branching still further; from the branch which accompanies 

 the winding only seen on the right side a long branch is sent otT to the lip of the 

 genital organ; this branch accompanies for a long distance the branch artery from 

 which it arises. 



Concerning the venous sj'stem I can only say that there are as usual two 

 anterior cardinal veins and two posterior (cp), of which the right is much larger 

 than the left. The caudal vein enters at the posterior end of the kidney. There 

 is only one very large vena hepatica (vh), remarkably long, as the liver lies behind 

 the elongated pectoral arch whilst the heart is in front. Into this flows the large 

 vein (up) from the muscles of the pectoral fins, the latter receiving a small vein 

 from the pubic arch and the ventral fins. 



The swim-bladder (s) is of very considerable size, spindle-shaped; it is 

 seen, as is well-known, through the dorsal cuirass. Its walls are very thin; at 

 about the middle of the ventral wall we find on its inner side a large, well- 

 developed rete mirabile, in shape like a horse-shoe with the concavity turned 

 posteriorly (it is slightly asymmetrical, the left side being somewhat longer than 

 the right). 



If an Amphisile is held up against the light, we can notice (in most specimens) 

 a thin, whitish streak passing from the under margin of the dorsal musculature 

 across over the swim-bladder and disappearing at the lower margin of the latter 

 under the opaque ventral plates; this is the nerve to the ventral fins. It comes out 

 through the incision in the transverse process of the 3rd vertebra, runs a small 

 distance backwards and then follows the course seen from the outside through the 

 dorsal cuirass to pass almost vertically down to the pubic arch. 



Genital organs. The ovary (go) is unpaired; it has transverse lamellæ 

 (A. scutata) and lies behind the end of the swim-bladder along the under side of 

 the kidneys. At about the posterior end of these it is reduced to a long, siring- 



