34 Transactions Texas Academy of Science. — 1906 . 
tire surface of the patagium and extending to the posterior border 
of the ulna. There is a narrow band along the posterior border of 
the humerus. The alula bears six strong feathers which extend 
from its distal extremity around its posterior border to the base. Be- 
ginning at the base the feathers increase in length successively till 
the sixth is reached which is the shortest of all, the fifth being the 
longest. Along the anterior margin occur contour feathers. There 
are ten primaries which become successively shorter from the wrist to 
the hand. There are twelve secondaries, and the wing is quin-cubital. 
The strong femoral tract runs into the dorsal tract, and grows weak 
as it crosses to the knee. The dorsal surface of the thigh is sparsely 
covered. The feathering of the leg extends to the heel and is not 
dense except along the posterior and anterior borders. 
The ventral tract merges anteriorly with the lower cervical and 
the humeral tracts. Near the clavicle two rows median to the main 
tract separate from it, and continue to the small tract in front of 
the anus, where it is joined by a single row which comes from the 
extremity of the main tract. On the ventral surface of the wing 
the feathers are distributed along the margins, over the alula and 
between the patagium and the ulna. The crural tract consists of 
a narrow band along the posterior edge of the leg down to the heel, 
but not reaching the ventral tract. At the anterior border of the 
leg it is joined to the ventral tract, and along this border is fairly 
dense. From this rows extend out to near the middle of the leg. 
There are ten rectrices. On the dorsal surface there are five 
coverts. On the ventral only four were found. At the base of the 
oil gland is a semicircle of six small feathers. On the ventral sur- 
face there is a dense tract on each side of the tail. The anus is al- 
most surrounded by a small tract. 
B. Conclusions. 
The following comparisons are limited to the genera described in 
this paper and to Phalaenoptilus treated in my previous one, partly 
because much of the literature on this subject was inaccessible, but 
mainly because I desired to limit the comparisons to genera person- 
ally examined. 
In the myology there are some exact agreements and many close 
resemblances. All the birds agree in the presence of an oil gland, 
a spleen and a gall bladder; in the absence of the biceps slip and 
powder downs; in the number of pancreatic branches and ducts. 
Characters which show differences are given in the following table. 
