232 



NORTH AMERICAN FAUNA 68 



Figure 92. — Early fetal stages of the sea otter. Sex could not be determined 

 in either specimen by gross examination, and the age of the fetuses is not 

 known. Differentiation of the front and hind limb buds has barely begun 

 in the larger fetus. Specimens from Amchitka Island, 18 and 19 March 

 1963: Left— Specimen JEB 63-52, weight 0.692 g., crown-rump length 17 

 mm. (KWK 65-18-15) Righl^Specimen JEB 63-67, weight 1.12 g., 

 crown-rump length 24 mm. (KWK 65-18-9). 



and described in detail by Sinha (1965). The development of the 

 fetal membranes, their structures, and evolutionary relationships 

 v^ere studied and described by Sinha and Mossman (1966). The 

 general appearance of the gravid reproductive tract is shown in 

 figure 93. 



NONPREGNANT ADULT FEMALES 

 Spring sample 



Although tv^o spring samples (1962 and 1963, table 46) of 

 female sea otters from Amchitka v^ere taken, I studied only the 

 1963 specimens. 



Between 15 March and 2 April 1963, 125 adult female sea otters 



