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 fishes. 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 Fverasfer. 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, 
fraja nasuta (59). In 1884, McKenzie published a most excel- 
lent paper on the catfish, Amezurus catus (52). He gives one 
figure showing the union of the efferent branchial arteries to 
form the carotids, dorsal aorta, etc., and finds the pseudo- 
branchiz, 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 Zodlogy (53), there is one figure and a 
very good description of the circulation of the dogfish, Scy/- 
fium canicula. By far the best account that we have of the cir- 
culation of selachians is found in T. J. Parker’s memoir on 
Mustelus (60), which was published in 1886. 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 
