48 Journal of Comparative Neurology. 



In later stages this organ seems to disappear, but a glance 

 at Fig. 3 will show that it becomes amalgamated with the stalk 

 of the hypophysis, In the stage figured, the pituitary has 

 acquired its glandular form and has nearly severed its connection 

 with the pharnyx. The chorda has become encased in the car- 

 tilage of the future basis cranii, but there are still ill-defined 

 rudiments of the connecting cord. \_Ch. con. and x. Fig. 3.] 

 The cause of the union of the two bodies is obviously the in- 

 creasing of the head-flexure and development of the saddle-cleft. 

 Fig. 4 illustrates the poorly developed pharyngeal sac of the 

 chick at about four days. 



II. The Pineal and Parietal Organ in Phrynosoma 



CORONATA. 

 By A. D. SORENSEN. 



The external appearance of the pineal organ in Phrynosoma 

 has been so amply described that futher mention of it need not 

 be made here. The different structures associated with the 

 epiyhysis and their interrelations have not, I think, been fully or 

 satisfactorily determined. 



In an article which appeared in the Bulletin of the Museum 

 of Comparative Zoology for 1890, Mr. W. E. Ritter has given 

 a detailed discription of the epiphysial structures of P. dou- 

 glassii and P. coronata. Among the sections of different groups 

 of which a comparative study of the epiphysial structures is 

 being made, a number of sections of P. coronata have been 

 studied and relations have been found to exist which do not 

 appear in Mr. Ritter's drawings. 



The Parietal Organ. The position of the parietal organ 

 with reference to the parietal bones, is not the same as described 

 by Ritter in either of the three different animals that have been 

 studied. No pit or even depression appears below the organ. 

 The terminal points of the parietal bones differ somewhat in 

 their positions as related to the parietal organ. The preparietal 

 bone lies in the normal position, while the post parietal bone 

 appears to project backward, the parietal organ lying in a straight 



