THE SEA OTTER IN THE EASTERN PACIFIC OCEAN 233 



Figure 93.~Intermediate fetal development. One side of the uterine wall was 

 removed to show the chorioallantoic placenta (^4) and the large antime- 

 sometrial, pedunculated saclike hematome (B) . The specimen on the left 

 shows also smaller hematomic pouches surrounding the hemotomic peduncle. 

 The relative size of the ovary is shown. It was sectioned to reveal the large 

 corpus luteum (C). Specimens from Amchitka Island: Left — specimen 

 JEB 63-40, weight 11.82 g., crown-rump length 53 mm., sex $ ; taken 17 

 March 1963. (KWK 65-18-33) Righl^-specimen ADFG 520, weight 61.95 g., 

 crown-rump length 105 mm., sex $ ; taken 2 August 1963. (KWK 65-13- 

 11) Sinha and Mossman (1966) give a detailed description of placentation 

 in the sea otter. 



were taken and their reproductive tracts were examined (table 

 51). Thirty-seven (30 percent) showed no evidence of pregnancy 

 (no corpus luteum or visible conceptus). Of these, 29 exhibited 

 evidence of being post partum from a few days to perhaps a year. 

 Among these 29 females that were judged to be post partum, 13 

 (45 percent) were accompanied by a pup. The remaining 16 (55 

 percent) were not, or the pup was not seen, but the female showed 

 anatomical evidence of having borne a pup. Although it might be 

 inferred that the loss of young is as high as 55 percent, this is not 

 necessarily true. Large young, although still dependent on their 



