The proof of intergradation, or the lack of it, between the two alleged species, Conepatus mearnsi and Conepatus leuconotus, would seem to be profitably sought by obtaining specimens along the Rio Grande in Texas between the Blocker Ranch ("50 miles southeast of Eagle Pass") and Laredo.
Measurements illustrating the size difference between the two alleged species are as follows:
Table 1. Measurements of Conepatus from Texas
| Column Heading Legend: | |
| Col. A: | ♂ ad. 186455 USNM, Mason, Texas. Type |
| Col. B: | ♂ ad. 31970/24575 USBS, Blocker Ranch, Texas |
| Col. C: | ♀ ad. 126241 USBS, 8 mi. S Langtry, Texas |
| Col. D: | ♂ ad. 47122 USBS, Brownsville, Texas. Type |
| Col. E: | ♂ ad. 45132/33129 USBS, Brownsville, Texas |
| Col. F: | ♂ yg. 45900/33865 USBS, Brownsville, Texas |
| Col. G: | ♀ ad. 47121/34865 USBS, Brownsville, Texas |
| Col. H: | ♀ ad. 24839/32237 USBS, Laredo, Texas |
| Col. I: | ♀ ad. 24840/32328 USBS, Laredo, Texas |
| Col. J: | ♂? sad. 16651 AMNH, Kingsville, Texas |
| C. mesoleucus mearnsi | C. leuconotus texensis | |||||||||
| A | B | C | D | E | F | G | H | I | J | |
| Total length | 633 | ... | 610 | 800 | 920 | 770 | 670 | 685 | 700 | ... |
| Length of tail | ... | ... | 269 | 360 | 410 | 300 | 250 | 220 | 260 | ... |
| Length of hind foot | 72[1] | 75[1] | 71 | 74 | 70 | 90 | 65 | 78 | 80 | ... |
| Condylobasal length | 72.0 | 72.8 | 64.5 | 83.5 | 78.9 | 78.2 | 72.0 | 75.7 | 74.5 | ... |
| Zygomatic breadth | 51.3 | 50.1 | 43.4 | 55.3 | 76.8 | ... | 48.3 | 49.0 | 48.0 | 50.3 |
| Mastoidal breadth | 41.0 | 44.2 | 37.0 | 47.3 | 78.2 | 43.7 | 40.5 | 40.5 | 40.7 | ... |
| Length of upper tooth-rows | 28.9 | 29.8 | 31.8 | 28.9 | 28.0 | 25.8 | 32.7 | 55.3 | 30.4 | 29.9 |
| Outside length of P4 | 7.3 | ... | 6.1 | 8.5 | 53.2 | 7.5 | 7.5 | 6.6 | 7.7 | 7.6 |
| Outside length of M1 | 7.8 | 7.0 | 6.7 | 9.2 | 52.7 | 8.4 | 8.3 | 7.6 | 9.3 | 9.1 |
| Breadth of M1 | 7.6 | 7.0 | 6.5 | 9.3 | ... | 8.6 | 8.2 | 7.9 | 9.4 | 8.2 |
[ [1] Measured dry.
Conepatus mesoleucus venaticus Goldman
When Goldman (Jour. Mamm., 3:40, February 10, 1921) named C. m. venaticus from Arizona he did not mention material which Merriam (Proc. Biol. Soc. Washington, 15:163, August 6, 1902) had recorded from Ft. Verde, Arizona, under the name Conepatus mesoleucus mearnsi. This material seems to be specimens in the American Museum of Natural History of which the two oldest specimens are as follows: No. 2486/1921, male, adult, from Box Cañon, 20 mi. S Ft. Verde; No. 2487/1922, female, subadult, from Verde River, Arizona. Pertinent measurements of these specimens are, respectively, as follows: condylobasal length, 72.4, 68.8; zygomatic breadth, 50.0, 44.2; width of braincase at constriction behind zygomata, 36.4, 33.8; mastoidal breadth, 44.3, 38.4. Comparison of these measurements with those given for C. m. venaticus (Goldman, loc. cit.) reveals that the specimens concerned agree in narrowness of skull with C. m. venaticus (C. m. mearnsi is relatively wider) and it is on this basis that we refer the specimens to Conepatus mesoleucus venaticus.
Urocyon cinereoargenteus costaricensis Goodwin