No. I.] DESMOGNATHUS FUSCA. 239 



this region. Its trabecular character also suggests the prob- 

 ability of the presence of lymph. 



Blood Supply. 



The difficulties of tracing out the circulation in such a small 

 animal, where injection is impossible, are obvious enough. 

 The general description of the blood-vessels of the cerebro- 

 spinal nervous system of the urodeles, as demonstrated by 

 Schobl (50), in Salamandra maculosa, Triton, Proteus, Amblys- 

 toma, and Necturus, it is believed, will, in all essentials, 

 correspond with the conditions incidentally observed in the 

 Desmognathus. The substance of the brain and myel contains 

 neither arteries nor veins; these lie upon the surface; they are 

 very much branched, and send capillary loops into the interior. 

 These vascular loops have also been noticed by Mrs. Gage. 

 Schobl describes and figures the loops as continuing nearly to 

 the endymal line. In the Desmognathus most of these loops 

 stop at the margin of the entocinerea, but occasionally they 

 have been seen to enter it a greater or less distance. The 

 carotid arteries, on entering the cranial cavity, divide into a 

 cephalic and caudal ramus ; the former passes along the side of 

 the mesencephal to the optic nerve, where it bifurcates; one 

 branch, the inferior external, passes along the latero-ventral 

 aspect of the hemicerebrum to the olfactory nerve, and gives 

 off numerous branches to the ventral and lateral aspects ; the 

 other — the superior internal artery — supplies the dorsal sur- 

 face of the cerebrum, passing along its dorso-mesal edge, and 

 giving off a branch to the supraplexus. Occasionally, on the 

 ventral aspect, a strongly-developed branch from the inferior 

 external artery meets its opposite, and forms a cephalic com- 

 municating artery. 



The caudal rami bend meso-caudad and anastomose ventral 

 to the hypophysis, thus forming a caudal communicating artery 

 from which springs the spinal artery by means of two or three 

 roots. The posterior communicating artery gives off two 

 branches, each one supplying the ventral, lateral, and, to some 

 extent, the dorsal aspects of the mesencephal; still another 



