Humphrey, Brain of the Snapping Tuttle. yj 



spindle shape. It is attached to the roof of the diencephal by 

 a narrow stalk, from its attachment it enlarges, passes slightly 

 cephalad and then tapers to a blunt point. It is closely 

 wrapped by blood vessels and by means of these and some 

 arachnoid threads is attached to a cartilage that lies against the 

 roof of the cranium, from which the cartilage is easily detached 

 in removing the brain from the dorso-lateral aspect. For this 

 outgrowth as a whole, I can find no satisfactory name. It con- 

 sists of three portions, epiphysis, dorsal sac and paraphysis. 

 Conarium would be the most fitting term, but this has already 

 been applied to the epiphysis alone, and Burckhardt (12) has 

 further complicated matters by applying it to. the paraphysis, in 

 his paper on the brain of Protopter us. I have therefore used 

 dorsal outgrowth to designate this structure as a whole. On the 

 ventral surface, directly ventrad of the attachment of the dorsal 

 outgrowth, is found the infundibulum. It has a conical form 

 with the base attached to the ventral portion of the diencephal 

 and the apex projecting caudo-ventrad ; to this apex is attached 

 "the hypophysis — a disk shaped mass, lying imbedded in a cup- 

 like cavity of the cranial floor. These structures will be de- 

 scribed at greater length subsequently. 



Segments of the Brain. 



Rhincncephal. — Although the olfactory lobes are usually 

 not considered to constitute a segment of the brain, yet they 

 will nevertheless be spoken of independently and not as parts 

 of the cerebrum. 1 These lobes are well developed, their length 

 being 60 per cent, of the length of the cerebral hemispheres. 

 Their outline from the dorsal aspect (Fig. 1) is ellipsoidal with 

 the greater transverse diameter near the cerebrum, the mesal 

 aspects of the bulbs are closely apposed but not fused in any. 

 way. Each lobe contains a cavity, the rhinoccele, which is 

 connected with the cavity of the corresponding hemicerebrum. 

 From a lateral view the olfactory lobes approach the rectang- 

 ular in outline (Fig. 3). Each olfactory nerve arises in two 



J For a discussion of this question see Wilder (94) and Mrs. Gage (30), 



