The Brain of Diemydylus Viridescens 309 



Fig. 42. An enlargement of the next dorsal section from Fig. 36. X 

 60. The ventral curve of the callosum between the two pillars is sup- 

 plied from a section from another series which was thicker. Shows the 

 relation of the intercerebral pia; the vessels of the auli-and paraplexuses; 

 the portEe and Ammon's horn ; two layers of cinerea in the thalamus. 



Fig. 43. An enlargement of Fig. 37. X about 32. The nerve tract 

 is a composite from two sections and shows a bundle from the myel 

 giving off a few fibers to the nth nerve, the rest continuinj.^ cephalad 

 as the ascending solitary bundle. The relations of the 7th and 9th to 

 the pia are shown. 



Fig. 44. An enlargement of Fig. 39. X 32. Shows the origin of the 

 3d nerve and of fibers from the same region which unite with the 5th 

 nerve, also the commissure of the 3d. 



Fig. 45, 46, 47. Frontal sections through the ventral, middle and dor- 

 sal parts of the crista, show the fibres and loop of vessels which it con- 

 tains. X 125. Near the level of figure 38. 



Fig. 48, 49. Frontal sections through the crista and part of the fornix 

 of the cat. 49, is through the larger portion of it, and 48 through the 

 more ventral part which continues as a slight ridge from it. The direc- 

 tion of rows of cells is indicated by dots. A blood vessel penetrates 

 nearly to the crista. X 6. 



Fig. 50. A frontal section more ventral than Fig. 40, through the 

 infundibulum, saccus and portion of the hypophysis to show the 

 membranes. 



PLATE V. 



Fig. 51. Transection of the brain of an adult, male diemyctylus, 5.3 

 cm. long, stained in carmine. X 125. Near the level of 18, Fig. 6. 

 Shows tiie callosum and two parts of the precommissure separated by 

 cells ; at f, fibers cut transversely which may represent a fornix as they 

 can be traced cephalad of the portae ; the paraphysis cephalad of its 

 opening into the cavities ; loops of capillaries penetrating even so far 

 as the callosum ; and processes from the brain substance toward the pia. 



Fig. 52. A nearly median, sagittal section, of the roof of the dien- 

 cephal of an adult, female diemyctylus, 10 cm. long. X 125. Shows 

 the paraphvsis ; the epiphysis with a few fibers from its caudal end ; 

 the supracommissure with processes from the endymal cells extend- 

 ing into it ; and the transition of these cells, to those of the diaplexus. 



Fig. 53. An enlargement of the paraphysis and its union with the 

 cavity as seen in Fig. 21. X 125. Shows the pigmented dura, the 

 vessels of the supraplexus, and the endyma of the pallium. 



Fig. 54. A frontal section of a large (7 cm. long) red form. X 120. 

 From the dorsal part of the metaplexus to show the lack of continuity 

 in endymal cells at its caudal end (cf Fig. 55). 



Fig. 55. Part of a transection from an adult female, 7. 7 cm. long, 

 corresponding in level with 30 Fig. 6, to show the metapore. X 120. The 

 endyma is recurved and covered by a granular matter at the opening. 

 The pia with vessels ceases, the dura is lined throughout by arachnoid 

 cells, (cf Fig. 30). 



Fig. 56 A more caudal part of the same section as Fig. 52 to show 

 the metapore near the meson. X 120. 



