The Brain of Diemydylus Viridescens 269 



off an almost complete investment for the siipraplexus (Fig. 

 51, 53), a somewhat partial one for tlie hypophysis (Fig. 50, 

 23) ; filling a large space (Fig. 28) caudad of the more spongy 

 part of the metaplexns ; surrounding the protrusion of the 

 endolymphatic sacs into the cranial cavity (Fig. 8) ; following 

 out the nerves from the cranial cavity (Fig. 40, II) and sur- 

 rounding their ganglia (Fig. 24, 39). 



The endolymphatic sacs (^Fig. 8) unite by a tube with the ear, 

 appearing as Norris (36) has shown in amblystoma. They 

 extend cephalad each side of the mesencephal (Fig. 35-37, 

 23-27), with diverticulums passing caudad of the mesence- 

 phal approaching each other over the metaplexus where the 

 cavities of these sacs and of the brain are brought into very 

 close contact (Fig. 37). In one specimen the sacs unite 

 over the meson (Fig. 34) as they are said to in the frog. By 

 injection methods Rex (43) has studied the grosser vascular 

 supply of the brain of Triton crlstatus, and as far as the die- 

 myctylus has been studied it agrees closely with his results. 



Intermaxillary gland. — Cephalad of the brain, between the 

 nostrils, with its tubules very close to the nasal epithelium is 

 the intermaxillary gland with its duct opening into the mouth 

 between the choanae (Fig. 6, 35-40). Wiedersheim (49) at- 

 tributes the discovery of this gland to L,eydig, and gives a 

 full account of it. In the urodeles it extends farther' caudad 

 than in the anura, but he shows no such close apposition to the 

 brain as occurs in diemyctylus. Here the tubules ramify very 

 close to the brain not being separated from it by a bony 

 wall for some distance on either side of the meson. The com- 

 bined meninges in this situation are delicate. In fact its sepa- 

 tion from the brain is only slightly more pronounced than that 

 of the hypophysis. Its nervous supply is apparently from a 

 branch of the 5th which crosses the olfactory nerve (Fig. 41), 

 In young larvae the gland does not appear, but before the end 

 of the gilled larval stage it is well developed. In the red 

 forms it reaches its maximum development in correlation with 

 the greatly exaggerated glandular growths in the skin. In 

 this stage its greatest usefulness would be expected as the se- 

 cretion in other species is said to aid in securing food by mak- 



