Fig. 8. — Extrusible penis, characteristic of an adult raccoon. 
209, fig. 5) is reflected by its baculum, which is much 
shorter and thinner than the bacula from intact animals 
8-11 months of age, fig. 5. Castrated male No. 59, 
fig. 6, still had a nonextrusible penis and a small bacu- 
lum at 22 months of age. The bone of this animal is 
only slightly longer and heavier than the bone from the 
castrated raccoon 10 months of age (No. 209, fig. 5) ; 
it is much shorter and thinner than bacula from intact 
males 18-23 months of age (Nos. 146, 87, 121, 200, 51, 
and 138, fig. 6). Although the photograph does not 
show it well, the baculum from the castrated raccoon 
22 months of age (No. 59, fig. 6) was dense like an 
adult bone and not spongy at the base, as are bacula of 
similar size from raccoons 12 months of age or younger. 
A method described several years ago (Sanderson 
1950: 395-6) 
two age classes based on whether the penis can be 
easily extruded through the preputial orifice was still 
found to be useful. 
for placing males, living or dead, into 
For intact males, a nonextrusible 
penis, fig. 7, indicates a juvenile, while an extrusible 
penis, fig. 8, indicates an adult. Lack of the male sex 
hormone in castrated male No. 59, which was discussed 
above, resulted in a penis that was nonextrusible when 
the animal was 22 months of age. The effect of pre- 
l4 
cocious sexual development, and presumably higher 
than average levels of the male sex hormone, on en- 
largement of the preputial orifice was shown by male 
No. 207 and male No. 308. Both were reared as pets. 
Male No. 308 had an extrusible penis at 5 months of 
age and an adult type baculum at 11 months of age, 
fig. 5. Male No. 207 had an extrusible penis when first 
examined at 9 months of age. He had an intermediate 
type baculum at 10 months of age, fig. 3. Although 
the penis is not a reliable character for aging male 
raccoons reared in captivity under all conditions, it is 
valid for separating wild males into two age classes, 
juveniles and adults, during the hunting and trapping 
season in Illinois. 
Although ossa clitoridae are present in some female 
Rinker 1944). Ages 
of females may sometimes be estimated on the basis of 
certain other sexual characters. 
raccoons, they do not indicate age 
For example, most nulliparous females are juvenile 
and all parous females are adult during the hunting 
and trapping season in Illinois. Most nulliparous fe- 
males may be recognized by their tiny, nonpigmented 
nipples. The nipples of parous females are longer; most 
of them are dark, but some are nonpigmented (Sander- 
