228 Bulletin American Museum of Natural History. [Vol. XXII, 



and also furnishes a good basis for the study of sexual and age difference 

 in the skull. Considerable space is here given to an exposition of 

 these features, in the belief that some of the results will be of interest 

 in other connections. 



The Coatis of western Mexico have been separated by Dr. Merriam 1 

 from those of eastern Mexico on the basis of "gray of the face more 

 restricted; tail longer; molariform teeth, particularly the upper ones, 

 very much larger and more massive." No measurements are given 

 of either the skull or teeth. The type locality of the western form 

 is Manzanillo, State of Colima, and I am indebted to Dr. Merriam for 

 the use of two topotype skulls, a fully adult male and female, for 

 comparison with the present material. I have also a small series of 

 specimens from the southern coast region of the State of Vera Cruz, 

 but only four of them are sufficiently mature for satisfactory compari- 

 son. In three of these the three upper molariform teeth (pm 4 -m 2 ) 

 have a combined length of 21 mm., and in the other a length of 22 

 mm. In the old male topotype the same measurement is 24 mm., 

 and in the female 22 mm. The same measurement in 30 adult 

 skulls from Escuinapa averages 22 mm., the extremes of the series 

 being 20 and 23.3 mm., none of them reaching 24 mm., but 6 reach 

 23 mm. Apparently the west coast animal is slightly larger than true 

 N. narica of the east coast, with rather heavier dentition. The 

 Sinaloa series averages somewhat lighter in coloration in comparison 

 with a dozen eastern specimens. But color is such a variable feature 

 in this group that little weight can be given to it in discriminating 

 races unless the material for comparison is extensive. 



Specimens from various localities in the northwestern part of the 

 State of Jalisco, from the Tepic border south to Ameca, aggregating 

 some 50 specimens, are not distinguishable in dentition and cranial 

 characters from the Escuinapa series. 



The collector's measurements of 38 adults from Escuinapa are 

 as follows: 14 males, total length, 1181 (1098-1264, with only i below 

 noo and only-i above 1200); head and body, 582 (533-629, with only 

 i below 559 and only 2 above 610); tail vertebrae, 591 (496-635, 

 with only 2 below 572, and only 2 above 610) ; hind foot without claws, 

 100 (89-108); ear from notch, 40.6 (38-44): 24 females, total length, 

 1103 (1041-1194, with only 3 below 1060 and only 3 above 1150); 

 head and body, 538 (496-597); tail vertebrae, 565 (533-598, with i at 

 635, the only one above 598) ; hind foot without claws, 92 (81-102); 

 ear from notch, 38 (32-44, only 4 below 38 and only i above 41). 



1 Merriam, Proc. Biol. Soc. Vol. XV, 1902, p. 68. 



