140 E. C. CASE 
arose in the phylum coincident with the development of adverse 
conditions were primarily of a physiological character affecting 
the deep-seated organs of the nervous system and through them, 
and only secondarily, the superficial structures. The terato- 
logical affections of the pituitary body which produced abnormal 
structures in a normal phylum may have gradually become a 
fixed character and resulted in normal giantism in certain groups. 
Similar correlations between other glands of the body and such 
characters as spines, horns, tusks, etc., which finally developed 
into excessive overgrowths in the senile stages of various phyla 
may have arisen in the same way. 
Since this manuscript was prepared two excellent figures of 
endocranial casts have been published: Osborn and Mook, 
Memoirs American Museum of Natural History, New Series, 
volume 3, part 3, plate LXIV, Endocranial cast of Camarasaurus 
supremus; Lambe, Canada Department of Mines, Memoir 120, 
fig. 27, Endocranial cast of Edmontosaurus. 
