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THE BLOOD-VASCULAR SYSTEM, 



DUCTLESS GLANDS, AND URO - GENITAL SYSTEM OF 

 AMIURUS CATUS. 



by t. Mckenzie, b.a., 



Fellow of University College, Toronto. 



The object of the present paper is to complete, as far as possible, 

 the description of the anatomy of Amiurus. The works of Stannius 1 , 

 Owen 2 and Wiedersheim 3 , have furnished the basis for the points de- 

 scribed, but special papers have also been consulted. 



I. THE BLOOD- VASCULAR SYSTEM. 

 This has been carefully worked out in the different groups of fishes, 

 and as the parts and relations in Amiurus are in the main similar to 

 those of other Teleostei, such general knowledge is assumed. 



THE HEART. 



The heart is situated entirely in front of the first vertebra. The 

 pericardium which encloses it, is in contact with the coracoids on the 

 ventral side. The hyopectorales muscles which arise from the inner 

 curved surface of the coracoids form the lateral boundaries, and 

 coming together anteriorly give a triangular shape to the cardiac 

 space. Above, it is covered by the floor of the mouth and the copulse 

 of the posterior branchial arches or their equivalents. The posterior 

 boundary is formed ventrally by the upward curve of the posterior 

 border of the coracoids, and dorsally by the aponeurotic membrane. 

 The stout coracoids are about 30 mm. wide. in the median line, and 

 extend from behind the sinus venosus to the upward curve of the 

 truncus arteriosus. It is plain that no other spot in the body out- 

 side the brain-case would afford such security to this vital organ. 

 The outer coat of the pericardium is more or less attached to the sur- 

 rounding surfaces. The heart lies free within the pericardium, which 

 is attached anteriorly to the truncus and post eriorly to the dorsal and 



i Handbuch der Anatomie der Wirbelthiere. 



2 Anatomy of Vertebrates. 



•3 Lehrbuch der vergl. Anat. der Wirbelthiere, 



