DE. J. MURIE ON THE OEGAJSflZATION OF THE CAAING WHALE. 269 



discussed by preceding authorities. In fig. 54 I give an illustration, by a transverse 

 section between two of the lumbar vertebrae, of the appearance of the cut vessels in 

 their recent state. Two immense veins lie on either side of the spinal cord, the 

 remainder of the space above and outside them being filled by a closely packed 

 reticular mass of venous and arterial channels of diminished calibre. The nervous 

 cord itself is small compared with the neural canal and vascular aggregation. The 

 deep lumbar plexus extends outwards from the side of the vertebral body to the tip 

 of the transverse process ; and in the intervertebral spaces branches communicate with 

 the spinal rete. A strong flat arch of fascia extends between the points mentioned, 

 and it binds down the retia, whilst superficial to it is the immense inferior lumbo- 

 caudal muscle. 



The plexuses are essentially composed of arteries and veins, varying in proportion 

 according to the situation. Besides the ordinary large and small vessels, there is a 

 vast congeries of capillaries of uniform calibre. Of the latter a primary series runs in 

 parallel lines, often straight, and frequently looped and contorted. Their diameter 

 may be compared to the thickness of a hog's bristle. They anastomose freely, bridging 

 and intercommunicating by acute forks, the divisions continuing parallel, either side by 

 side, or twisted like a rope, or occasionally tangentally twirling away from each other. 

 Besides the above capillary network, a subsidiary or secondary series springs from the 

 first. These, even when injected, are only half the diameter of a human hair, and in 

 their branches and ramifications diminish to a far finer tenuity. The secondary arise 

 everywhere from the first series, and often run alongside and between them ; so that 

 one of the primary may have several of its satellites spun around it in its course. The 

 finer ramifications, however, are by no means so regularly parallel, but split up into 

 thousands of divisions, branching and divaricating in all manner of ways, forming an 

 intercommunicating network, intertwined -ndth the loops of the primary series. The 

 venous radicals have an arrangement somewhat similar ; and their primary capillaries 

 lie in juxtaposition and are spread amongst the arterial series. 



By Himter and others it is said that in Cetacea the abdominal aorta does not send 

 off any external iliacs. I have found the following condition obtain in this female 

 G. melas. A little way beyond the inferior mesenteric artery and lumbar branches 

 there arose laterally and at right angles from the aorta two short wide stems, common 

 iliac arteries. Each of these was fully an inch long, and split into two divisions, or 

 what may be termed anterior and posterior. The former or hypogastric artery proceeded 

 forwards partly enwrapped by a fold of the uterine broad ligament. Abdominally to this 

 it went to the apex of the urinary bladder, distributing branches thereabouts, and 

 joining its fellow arteiy of the opposite side, ultimately constituting an umbilical artery, 

 which cord was nearly impervious. The latter or posterior division of the short aortic 

 stem, at two inches distance from the anterior one, bifurcated. One of these two 

 branches, which I take to be an external iliac, almost immediately beyond its origin 



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