104 MR. F. E. liEBDARB UN THE [Feb. 7, 



handed over to the Museum of the Royal College of Surgeons, 

 where will also be found some of the other brains described here. 



The basilar artery and the anterior spinal artery are qviite con- 

 tinuous. The junction of the two appears to be marked by the 

 exit of what I presume to be the homologue of the mammalian 

 vertebral arteries. These arteries join the longitudinal vessel on 

 either side in a rather remarkable way. The point of entrance is 

 not lateral, but ventral and median, that of the left side entering 

 posteriorly to the i-ight-hand vessel. These latter, moreover, give 

 off a forwardly-running branch, which diminishes in calibre and 

 effects a second junction with the basilar artery just at the point 

 where the latter receives the right cerebellar artery ; this entrance 

 into the basilar is also ventral and median. The minute details 

 being perhaps individual are not shown in the figure. The a^iterior 

 spinal ai'tery is double for a considerable distance behind the entry 

 of the vertebral arteries ; the two tubes, however, reunite. Both 

 the anterior spinals give off a large number of small trunks to the 

 adjacent regions of the medulla and spinal cord. 



The cerebellar iivtevYQB (text-fig. 15, C, p. 103) are large and con- 

 spicuous; the right-hand artery aiises in front of that of the left 

 side ; this asymmetry, it will lie noticed, exactly corresponds to that 

 of the vertebral arteries — i. e., the left vertebral artery, like the left 

 cerebellar, is posterior to the right. Each cerebellar artery, before 

 reaching the cerebellum, gives off a strong branch which forms the 

 posterior spinal artery. Of these, at least four I'un side by side 

 down the posterior face of the spinal cord, contrasting thus with 

 the single or, at least only for a short space, double anterior spinal. 

 The cerebellar arteries pass over the summit of the flocculus arid 

 supply all parts of the cerebellum. This region of the brain is, 

 however, also supplied from other sources, which will be dealt 

 with in due course. 



The basilar artery divides into two just in front of the third 

 nerves ; but the left-hand branch is much the larger, and indeed 

 the right-hand branch might easily escape attention. 



The carotid arteries (text-fig. 15, Ca., p. 103) lie at the side of the 

 pituitaiy body, and of course behind the optic nerves ; each artery 

 divides into two branches. The posterior branch runs between 

 the corpus bigeminum and the cerebellum, and receives immedi- 

 ately after its origin the lasilar artery. It supplies both corpus 

 bigeminum and cerebellum. The anterior branch curves round 

 the optic chia&ma and ends in the ophthalmic artery (text-fig. 15, 

 Opth.) of its own side : theie is thus no completed circle of Willis. 

 This main anterior trunk of the carotid has three branches. 

 The first runs between the corpus bigeminum and the cerebral 

 hemisphere, and along the inter-hemispheral sulcus, giving off 

 branches also to the cerebellum. The middle cerebral artery is 

 rather larger than the posterior. It nuis along the depression 

 which has been compared to the Sylvian fissure, giving off branches 

 right and left. It bifurcates, just at the junction of the lower 

 surface of the brain with the upper, into two main blanches, of 



