° 1915 J Shufeldt, Anatomy of the Passenger Pigeon. So 



I find the cerebellum to be 8 millimeters long and 6 mm. wide at 

 its middle part. It projects posteriorly considerably beyond the 

 cerebral hemispheres, and exhibits, on its strongly convex posterior 

 aspect, six transverse sulci, in which minute vessels ramify. The 

 optic lobes — one upon either side — are large and of an ellipsoid 

 form; they cover, in either case, the point of radiation of the sulci 

 laterally, which point (the flocculus) is frequently well exposed in 

 tame or domesticated pigeons. 



Having the usual form as seen in the Columbidoe generally, the 

 cerebral hemispheres are in contact with each other mesially and 

 with the optic lobes below. The cerebral vessels ramify super- 

 ficially upon the surface of each, while between them, posteriorly, 

 the small pineal gland is in view. Upon direct superior view, the 

 cerebral hemispheres nearly shut out the optic lobes from sight. 



Anteriorly, the olfactory lobes are well developed and project 

 beyond the hemispheres, — the first pair of cerebral nerves were 

 divided close to them. Likewise, the second pair of optic nerves 

 were divided close to the rather large optic tracts at the base of the 

 brain-mass. 



Measuring across the widest part of the cerebral hemispheres, I 

 find it to be a distance of 18 mm., while the length of the cerebral 

 sulcus is 9 mm. 



The Eye: In my above cited paper on the osteology of the 

 pigeon, I have already noted the characters of the sclerotic plates 

 (p. 360), and I may add here that the average antero-posterior 

 diameter of the eye is found to be 14 mm., its transverse diameter 

 being about 9 mm. There appears to have been nothing peculiar 

 in the external musculature of this organ, beyond what we find in 

 the typical eye of ordinary existing birds, — ■ the pigeons in particu- 

 lar. Posteriorly, the optic nerve is not surrounded by an " osseous 

 plate," as it is in the Raven. 1 



Internally, the pecten presents nothing unusual, and the lens has 

 a diameter of about 4.5 mm. 



My next procedure in this dissection required me to separate t!he 

 immense pectoralis major muscle from its origin upon the sternum 

 on the right side, and to deal with the pectoralis secundus and 



« Shufeldt, R. W. "Myology of the Raven," p. 60, fig. 23. 



