BLOOD-VASCULAR SYSTEM OF THE LORICATI 35 



During the last half century quite a number of important 

 papers have appeared on the circulation of different species of 

 fishes, or confined to the circulation of various organs, and a 

 few are devoted to the embryology and physiology of the blood 

 vessels. First under this head might be mentioned the first vol- 

 ume of Owen (58), which was issued in 1866. The author 

 gives a very good comparative description of the circulation in 

 several groups of lishes. Ten years later Stohr (75), described 

 the number and arrangement of valves in the conus arteriosus 

 of selachians and ganoids. In 1880, Emery (24) put out his 

 monograph on the genus Fierasfcr. This volume contains a 

 short, but accurate account of the circulatory system and 2 

 most excellent colored plates ; the first one consists of a figure 

 of the entire arterial system, a similar figure of the venous sys- 

 tem, and several figures showing the blood supply in the kid- 

 neys ; while the other plate is devoted to the blood vessels in 

 the organs. The same year T. J. Parker published a paper, to 

 which I have not had access, on the venous system of the skate. 

 Raja nasuta (59). In 1884, McKenzie published a most excel- 

 lent paper on the catfish, Ameiurits catits (52). He gives one 

 figure showing the union of the efferent branchial arteries to 

 form the carotids, dorsal aorta, etc., and finds the pseudo- 

 branchiae, though only rudimentary, located on the main inter- 

 nal carotid artery, and not on a branch of the external carotid 

 or hyoidean artery as is the case with bony fishes in general. In 

 Marshall and Hurst's Zoology (53), there is one figure and a 

 very good description of the circulation of the dogfish, Scyl- 

 Ihmi canicula. By far the best account that we have of the cir- 

 culation of selachians is found in T. J. Parkers memoir on 

 Mustelus (60), which was published in 1S86. It contains 47 

 pages and 4 most excellent colored plates. The author gives a 

 brief synonymy of the blood vessels, and his methods of inves- 

 tigation. Unfortunately I did not gain access to this valuable 

 paper, until my own work was nearly completed. Mayer (55), 

 in 1888, gives a detailed account of the circulation in the fins 

 of selachians, with 2 colored plates. The author gives the 

 technique employed and favors an aqua solution of Berlin blue 

 for an injection mass. The so-called peripheral lymphatic ves- 

 sels described by Hyrtl, Miiller, and Stannius, he considers as 



