The only exception was one wild female which still had 
broad epiphyses at approximately 17 months of age, 
table 5. If the entire carcass of this female had been 
examined she would have been placed in the adult age 
class because she was parous. Field data collected in 
the northern half of Illinois during the 1959-60 and 
1960-61 hunting and trapping seasons show somewhat 
comparable results. Only 3 of 140 females with stimu- 
lated nipples (parous females and those which under- 
went pseudopregnancy) had broad epiphyses. A ma- 
jority of the adult, wild, nulliparous females, identified 
by thin or closed epiphyses and no placental scars in 
their uteri, are 16-22 months of age at this season. In 
the wild in Illinois, only a few females older than 22 
months are nulliparous, because few female raccoons in 
this state fail to become pregnant in a breeding season 
after they are more than | year of age. 
ml 
iaee 
302 
Observations made on seven castrated females were 
inconclusive, table 5. The epiphyses of one castrated 
female were thin when the animal was 24 months of 
age and closed when she was 26 months of age. Those 
of another castrated female were thin when the animal 
was 21 months of age and closed when she was 30 
months of age. A third castrated female had thin 
epiphyses when she died at 23 months of age. 
In raccoons, epiphyseal cartilage plates in humeri 
close somewhat later than in radii and ulnae. Two ani- 
mals had thin plates in their humeri 3 months after the 
epiphyses of their radii and ulnae had closed. In four 
other animals, epiphyseal plates in the humeri were 
closed 4-9 months after closure in the radii and ulnae; 
no examinations were made in the intervening periods. 
It appears that epiphyseal plates in humeri close 3-9 
months after they close in the radii and ulnae. Epiphys- 
Fig. 4. — Juvenile-type bacula from raccoons 5 to 7 months of age showing the effects of age and castration on development. 
Grid squares represent one-half inch, 
No. 233: captive, 5 months old. 
No. 302: wild, estimated 5 months old. 
No. 226: captive, 5.5 months old. 
No. 228: captive, 5.5 months old. 
No. 225: captive, 6 months old, castrated. 
No. 235: captive, 6.5 months old. 
No. 50: captive, estimated 7 months old. 
No. 117: wild, estimated 7 months old. 
No. 292: wild, estimated 7 months old. 
No. 234: captive, 7 months old, castrated. 
