1873.] .157 [Putnam. 



In Myxine the duct leading into the end of the oesophagus has its 

 external opening close by the side of the left branchial opening, and 

 passes in front of the heart to the oesophagus. In both species of 

 Bdellostoma this duct also passes in front of the heart, and its exter- 

 nal opening is close by the last branchial opening on the left side, 

 thus occupying a position still further removed from the median line 

 of the abdomen than in Myxine. 



In Myxine the branchial artery passes from the heart forwards 

 along the under side and between the branchial sacs, giving off right 

 and left branches as it passes each sac, each branch passing over the 

 sac and entering it about in the centre of its posterior surface in close 

 connection with the duct leading from the gill. 



In Bdellostoma cirrhatum, from Cape of Good Hope, figured by 

 Miiller, 1 the branchial artery has the same course as in Myxine, but 

 divides into a right and left branch after supplying the three pair of 

 sacs nearest the heart, each branch giving oft' smaller branches to 

 the sacs of its own side. In Bdellostoma polytrema, from Chili, 1 have 

 in seventeen specimens found the branchial artery to be divided into 

 right and left trunks to its very base, and each trunk immediately 

 turns off to its respective side, crossing the first three sacs in its 

 course, and passing along the under edges of the rest, giving off 

 branches from its upper surface to each of the sacs. 



Owen mentions that in a specimen of B. cirrhatum the artery 

 was divided to its base, but he does not mention the region from 

 which his specimen came, nor the number of the gill sacs, and he 

 may have had a Chilian specimen of the genus. It will be interest- 

 ing to ascertain if this division of the artery is constant and charac- 

 teristic of the Chilian species. 



In Myxine the base of the long tongue is at the anterior branchial 

 sacs, and in Bdellostoma. cirrhatum, with its six or seven pair of gills, 

 the same is the case, while in B. polytrema, with ten pair of gills, the 

 tongue passes down between the first six or seven pair, and has its 

 base in front of the next pair, leaving but three or four pair between 

 the end of the tongue and the heart. 



In Myxine the eggs are developed along the free edge of the ovary> 

 which extends as a fringe as the eggs increase in size, and the eggs of 

 several stages of growth are always at the free edge. In the Chilian 

 Bdellostoma the ovary, even when the eggs are very minute, is devel- 



1 Under the name of B. heterotrema, Abk. Akad. Wissensck., Berlin, 1834. 

 pi. VII, fig. 3. 



