484 'Journal of Coinparative Neurology and Psychology. 



pituitary body, so in fishes the infundibular recess must be that 

 somewhat funnel-shaped or trough-shaped depression in the floor 

 of the inferior lobes which leads into the saccus vasculosus, this 

 being the neural portion of the pituitary body in fishes. 



The angle of ectoderm from which the hypophysis will be devel- 

 oped can be readily recognized by the stage when the depression of 

 the primitive optic groove has pushed the preoral entoderm out of 

 the way and come into contact with the ectoderm. The hypophysial 



Fig. 20. Squalus ac, 80 somites, median sagittal section, x 33. Pre- and 

 postoptic recesses, mamillary recess, epiphysis and velum transversum. 



ectoderm is in contact with the posterior surface of this depressed 

 part of the brain floor. As the hypophysis pushes in (Figs. 18, 19, 

 and following) its anterior limb remains in contact Avith the posterior 

 wall of the primitive optic groove. The hypophysis grows back in 

 contact with the rounded surface of the inferior lobes, insinuating 

 itself between the brain floor and the median mass connecting the 

 premandibular somites. As this mass in early stages connects the 

 anterior head cavities also with one another, it may be said that the 



