Fig. 7. — Nonextrusible penis, characteristic of a juvenile 
and adult age classes is discussed by Sanderson (1950:395-6). 
7 and 15 months of age respectively, had broad 
epiphyses. Male No. 308 had broad epiphyses (not 
shown) which were typical of males 10-13 months of 
age, indicating that epiphyseal closure and development 
of the baculum do not necessarily correspond. Bones 
shown from several other males revealed the conditions 
usually found. Two males (No. 147, fig. 3, and No. 319, 
not shown), 10 and 12 months of age respectively, had 
broad epiphyses and juvenile-type bacula, fig. 5. Two 
other males (No. 87, not shown, and No. 119B, fig. 3), 
19 and 20 months of age respectively, had thin epiphyses 
and adult-type bacula, and one male (No. 84, fig. 3), 
whose baculum was also of the adult type, had epiphyses 
which closed at approximately 17 months of age. 
X-ray photographs taken of several bacula from 
animals of known ages indicate that X-ray examination 
would place each male in the same age class it would 
be placed by visual examination of the baculum. Each 
baculum X-rayed from animals 10 months of age or 
raccoon. The penis as a means for separating males into juvenile 
less showed the absence of a dense layer of bone on the 
surface of the basal end. Some males 19-33 months old 
had bacula which showed the absence of a dense layer 
only at the extreme basal tip of each baculum, while 
others 18 and 23 months of age had bacula with a 
dense layer completely surrounding the bone. Further 
study might reveal some correlation between age and 
the relative thickness of the dense and spongy layers of 
bone at the basal end of the baculum. 
The level of sex hormones appears to affect enlarge- 
ment of the preputial orifice and maturation of the 
penis bone and perhaps has a slight effect on the age at 
which the epiphyses close. Bacula from captive rac- 
coons of known ages indicate that sex hormones have 
little or no effect on development of the bacula prior to 
the time the animals are 7 months of age. Fig. 4 shows 
bacula of raccoons of 5—7 months of age; Nos. 225 and 
The effect of lack of 
sex hormones in a castrated male 10 months old (No. 
234 are from castrated males. 
