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On the Rete mirabile of the Narwhal. 
By Dr H. 8. Witsoy. 
He divided his remarks into three parts. The first portion 
consisted simply of the anatomical facts derived from his dis- 
sections made of a fetal Narwhal. The second contained 
remarks on these dissections as far as they differed from ‘man 
and from the statements of authors who had investigated the 
subject. The third part embraced the teleological deductions 
derived from the facts recorded. In his first portion, after 
describing the principal sources whence the thoracic rete of the 
Narwhal derived its constituent vessels, and after pomting out 
wherein they differed from the arrangement of the same vessels 
in Man, Dr Wilson proceeded to give a minute account of the 
position, relations, and structure of the rete itself. He shewed 
that the rete was divisible into halves, each of which derived 
its constituent vessels from two sources, that these vessels were 
peculiar in presenting at their origin the same calibre, being 
very minute, and consisting of great numbers; that they arose 
from trunks of the aorta of primary or next to primary calibre, 
and that, thus, in position, the rete was central to the arterial 
system. He divided the constituent vessels of the rete into 
three sets, vasa maxima, v. media, and v. minima, giving their 
distinguishing characters, and concluded this part with the 
enumeration of the various structures found imbedded in the 
substance of the rete. The second portion of his paper had 
reference chiefly to the discrepancies existing between the notes 
from his dissections and the statements given by Hunter, 
Breschet, and Owen, on the thoracic rete of Cetacea in general. 
In his teleological deductions he attempted to bring the arterial 
retia mirabilia under headings by dividing them into two great 
classes, bilateral and axial. The axial he further subdivided 
into terminal and mediate, and each of these again into com- 
plete and incomplete. In commenting on the axial system he 
