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Pace” PROCEEDINGS OF THE NATIONAL MUSEUM. 447 
CATALOGUE OF SPECIES COLLECTED BY DR. ABBOTT. 
Colobus caudatus Thomas. 
This remarkably handsome monkey is regarded by Mr. Thomas as ¢ 
subspecies of Colobus guereza. So far as I know, however, no specimens 
showing external characters intermediate between those of the two 
forms have been found, and the skulls which Dr. Abbott brought home 
are different from that of C. guereza. On present evidence it may be 
affirmed that Colobus caudatus is a distinct species, veculiar to the re- 
gion of Mount Kilima-Njaro. 
The species would appear to be somewhat larger than C. guereza. The 
chief distinguishing character externally is the hairiness of the tail. The 
tail is clothed with long white hair from base to extremity, and resem- 
bles that of a horse, as is well shown in Mr. Thomas’s figure.* 
The differences between the skulls of the two species are many. The 
most striking relates to the form of the nasal bones, which are flat or 
even concave transversely in C. caudatus, so that they appear to lie in 
the same plane with the margin of the anterior nares when the skull is 
viewed in profile. In C. guereza, on the contrary, the nasals project 
strongly in the distal half. The interocular portion of the frontal is 
much narrower in C. caudatus than in C. guereza, the superior margin of 
the orbits is more arched and the forehead above them much more de- 
pressed. The facial portion of the skull in front of the eyes is broader 
and more convex in C. caudatus than in the allied species, and the ex- 
ternal rim of the orbits narrower. The tympanic bones are much the 
largest in C. caudatus, and their form as well as the relative positions 
of the various foramina are different. The mandible is less deep and 
more shelving at the symphysis in C. caudatus. 
Many of these differences are indicated in the accompanying table of 
measurements. They are sufficient, | am satisfied, to warrant the sep- 
aration of C. caudatus from C. guereza as a distinct species, though the 
two forms are closely related.t 
The largest skull of C. caudatus in the collection (No. 34680), which 
has a basilar length of 91.4 millimeters, has the suture between the 
occipital and sphenoid still open and the teeth very little worn. 
* Proc. Zobl. Soc., London, 1885, pl. 12. 
tI may say, in confirmation of this opinion, that when a skull of CO. guereza was 
placed in the midst of five or six skulls of C. caudatus it was immediately selected 
from the others by three persons to whom the question at issue was unknown. 
