22 
Transactions Texas Academy of Science. — 1906. 
is 18mm., the greatest width 13.25mm. In Aeronautes (Cer., PL V., 
figs. 38, 39, 40) the greatest length is 12mm., greatest width, 8.25mm. 
The anterior-posterior measurement of the optic lobes in Geococ- 
cyx (Op. L, PL I., figs. 1, 2, ;3 ) is 2mm., and the dorsal- ventral 
measurement is 4.25mm. In Aeronautes (Op. L, PL V., figs. 38, 39, 
40) the anterior-posterior measurement is 1.125mm., the dorsal- ven- 
tral measurement is 2mm. 
The length of the cerebellum in Geococcyx (Cb., PL I., figs. 1, 2, 
3, 7) is 18.125mm., width from flocculus to flocculus is 12mm. The 
corresponding measurements in Aeronautes (Cb., PL V., figs. 38, 
39, 40) are 11 :5mm. and 7.75mm. 
It was not possible to get the measurements of the brain of Bubo 
because of its torn condition. 
All the cranial nerves of Aeronautes could not be identified on 
account of being broken. 
The brachial plexus is made up of four nerve roots in Geococcyx 
(PL I., fig. 7a), four in Bubo (PL IV., fig. 31), and five in 
Aeronautes (PL V., fig. 41). The branching and anastomosing is 
most complex in Aeronautes and simplest in Bubo . 
The sacral plexus consists of seven nerve roots in Geococcyx (PI. 
I., fig. 4) and of five in Aeronautes (PL V., fig. 46), most complex 
in the former. The spinal cord was too broken for it to be studied 
in Bubo. 
4. Special Sense Organs. 
The nostrils in Geococcyx (Nos., Pl. I., fig. 2) are median, inferior 
and oblong. The internal nares (I. n., Pl. I., fig. 12) is a single 
median club-shaped opening. These organs were not studied in 
Bubo. The nostrils in Aeronautes (Nos., PL V., fig. 38) are tubular, 
and larger near the opening than elsewhere. The internal nares 
(I. n., PL V., fig. 44) is a very long, median, irregular slit. 
The pecten of the eye in Geococcyx (PL I., figs. 5, 6) consists of 
sixteen folds. It measures in height 4mm., and its basal breadth 
is 7.25mm. In Bubo (PL IV., figs. 35, 36) it consists of eight folds. 
The corresponding measurements are 7.125mm. and 6.125mm. In 
Aeronautes (PL V., figs, 42, 43) there are fourteen folds. The 
corresponding measurements are 3mm. and 5mm. In all cases 
the pecten is heavily pigmented. 
5. Myology. 
a. Pectoral Muscles. 
1. M. pectoralis. — Pars thoracia. The origin in Geococcyx 
(Pect., PL II., figs. 14, 17) is on the clavicle, the ventral third of 
the anterior half of the carina sterni, all its posterior portion and 
