GALEUS COMMUNIS. 403 



the tail : they are conglomerated like those of a bird : the ureters come 

 out of this substance about the middle, and lie on the surface ; each 

 ureter opening into a bag which lies behind the oviducts in the female, 

 which bags communicate at the lower part, and open by one orifice just 

 within the ring of the anus, next to the back. These bags run up the 

 back close to the kidney at the insertion of the mesoarium, becoming 

 smaller and smaller. The urine is a thickish mucus. 



The heart has but one auricle and one ventricle 1 . There is a pair of 

 valves at the opening of the vena cava which are pretty long. The 

 auricle is large and thin in its coats, and a good deal fasciculated on its 

 inner surface. The valves between the auricle and ventricle are two, 

 and not nearly so long as those between the vena cava and auricle, but 

 they are stronger. The branchial artery begins at the upper part of 

 the ventricle, but is muscular at the beginning for nearly an inch, and 

 then becomes elastic before it gives off any of the branchial arteries ; 

 upon its inside are placed three valves, something like the tricuspid 

 [valves of the right ventricle in man], which have cords passing out 

 from their points to be fixed to the semilunar valves at the beginning 

 of the true elastic artery : the corpora sesamoidea are very large. The 

 coronary arteries do not arise from the branchial artery that comes out 

 of the heart ; so that the alternate contraction of the heart cannot arise 

 from the coronary arteries arising behind the valves. 



Near the upper part of the oviduct are two cseca, like those of the 

 rectum of some carnivorous birds : these are partly enclosed in an entire 

 peritoneal capsule. The one I had from Dr. John Hunter might be 

 called a maiden one. The oviducts were no larger than crow-quills : 

 they winded round the upper part of the liver, on the spongy substance, 

 and bent a little down between the two lobes, and, as it were, joined 

 [one another], and opened by a slit between the upper part of the two 

 lobes 2 . The ovaria are two long bodies lying on the back behind the 

 upper part of the liver. 



There is no dura mater either to the brain 3 or medulla spinalis. An 

 elastic ligament runs along the spinal processes of the back, from the 

 head. The nerves of the head mostly terminate in the blind ends of the 

 mucus bags or canals, which are in vast numbers in the head, in many 

 places close upon one another, like a honeycomb. They [sharks] have 

 no cauda equina, the medulla spinalis terminating in the tail in a point. 

 The nerves from the medulla spinalis are very small : their number seems 

 to be equal to the number of interstices between the vertebras. The 



1 [Hunt. Prep. Phys. Series, No. 911.] 2 [lb. No. 2679.] 



s [lb. No. 1311.] 



2n 2 



