20 
Transactions Texas Academy of Science. — 1906. 
fig. 34) it is broad and thick. It is also bifid posteriorly and covered 
thickly with spines. In Aeronautes (T., PI. V., fig. 45) it is broad 
and thick, but is pointed anteriorly and slightly bifid. Posteriorly 
it is bifid and covered closely with spines. 
The crop is absent in all. The duodenum in Geococcyx (Duo., 
PI. I., fig. 13; PI. II., figs. 21, 22) measures 12.3cm.; the small in- 
testine (PL II., fig. 22), 28.9cm.; the terminal intestine (PL I., 
fig. 11; Pl. II., fig. 22), 10.4cm.; caeca (Cae., Pl. I., fig. 11; Pl. II., 
fig. 22), 6.1cm. In Bubo the measurement of the duodenum (Duo., 
Pl. III., figs. 24, 29) is 20.8cm.; the small intestine (Pl. III., fig. 
29), 45.5cm.; terminal intestine (Pl. III., fig. 23), 7.5cm.; caeca 
(Cae., Pl. III., fig. 23), 8.2cm. In Aeronautes the measurement 
of the duodenum (Duo., Pl. V., figs. 47, 48, 49), is 13.1cm.; small 
intestine (Pl. V., fig. 49), 6.4cm. (this is from duodenum to begin- 
ning of the cloaca) ; terminal intestine (PL V., fig. 49), 1.8cm. In 
both Geococcyx and Bubo the caeca are enlarged at the tips. The 
type of the intestine in Geococcyx is a modification of the plagiocoel. 
In Aeronautes it is orthocoel. 
The pancreas in Geococcyx (Pan., Pl. II., fig. 21), and Aeronautes 
(Pan., Pl. V., figs. 47, 48, 49), consists of two branches, one being 
situated in the duodenal loop and the other dorsal to it. There is 
one duct from each branch and in all cases they enter the ascending 
branch of the duodenal loop. In Geococcyx the entrance is posterior 
to the bending of the duodenum to pass under the right liver lobe, 
and in Aeronautes it is at the mid point of the ascending loop. The 
pancreas was not in a condition to be studied in Bubo (Pan., Pl. 
IIP, fig. 29). 
A spleen is present in all the forms, and is situated on or near 
the junction of the proventriculus and the gizzard, at' the right side. 
The organ is small in Aeronautes (Spl., Pl. V., fig. 48), but very 
large in Geococcyx (Spl., PL I., fig. 13), and Bubo (Spl., PL III., 
fig. 29). Its length in Geococcyx is 13mm., its average width 5mm. 
The length in Bubo is 25mm., the average width 10mm. The length 
in Aeronautes is 5mm., the average width 2mm. 
The liver of Geococcyx (Liv., Pl. II., fig. 21) consists of two lobes, 
the right being fully one-third larger than the left. In Bubo (Liv., 
Pl. III., figs. 24, 29) the lobes are of almost equal size. In Aero- 
nautes (Liv., Pl. V., figs. 47, 48, 49) the right lobe is a third larger 
than the left. On the dorsal border of the right lobe is a third lobe 
one-half the size of the left lobe. 
A gall bladder is found under the lower border of the right liver 
lobe in all the birds. Its length in Geococcyx (G. bl., Pl. I., fig. 13) is 
11mm., the average width is 4mm.; the length in Bubo (G.bl.,Pl.III., 
