Table 35. — Accuracy of identification of placental soar^ 



During examination of each pair of uterine horns, 

 judgment was made as to the presence or absence of a 

 placental scar. Later, during examination of the ovaries, 

 the presence or absence of a corpus albicans did or did 

 not substantiate the judgment. 



Table 36. — Frequency of diameters of uterine horns in fur 

 seals, by month 



Total 13 24 12 49 13 24 12 49 



Msan, mm. 20.5 21.3 21.6 21.2 17.3 17.4 17.8 17.5 



■^ External diameter of freshly thawed horn measured at its 

 midpoint. 



The fur seal has a bicomuate uterus. 



In 41 tracts, the horn of the albicans side 

 was larger (up to 12 mm. larger) than the 

 horn of the luteum side. In six tracts the 

 horns were equal. In two tracts the horn of 

 the albicans side was 3 mm. smaller than the 

 horn of the luteum side. 



ERRORS IN DETERMINING AGES OF FUR 

 SEALS FROM CANINE TEETH 



Methods used at the Marine Mammal Bio- 

 logical Laboratory to collect and prepare 

 teeth and determine ages were described by 

 Scheffer (1950b) and Fiscus, Baines, and 

 Wilke (1964), To test the accuracy of the 

 method, right upper canine teeth collected 

 from male and female seals of known age 

 that had been tagged as pups on the Pribilof 

 Islands and killed later there or at sea were 

 given to four readers. The readers had no 

 knowledge of the correct ages. 



The tests were based on whole and on 

 sectioned teeth because the ages of most seals 

 killed on the Pribilof Islands have been de- 

 termined from whole teeth, whereas the ages 

 of those taken at sea have been based on 

 sectioned teeth. Each reader read each tooth 

 twice. Conference readings were not made for 

 whole teeth of males or females, or for sec- 

 tioned teeth of males. Because the teeth of 

 males are much larger than those of females, 

 the tests for each sex are discussed separately. 



Males 



A sample of 380 whole teeth from males 

 2 to 5 years old was used in the tests. Ages 

 2 to 5 were selected because nearly all males 

 killed on the Pribilof Islands are within this 

 range. Reader error increased from a range 

 of 2.0 to 6.1 percent for 2-year-olds to a 

 range of 2,5 to 28.1 percent for 5-year-olds 

 for two readings (table A-21). Ninety-nine 

 percent of the assigned ages were within plus 

 or minus 1 year of the correct age. Reader A 

 had the lowest error (table 37). 



For 120 sectioned teeth from male seals 

 in ages 2 to 5, errors ranged from to 33.3 

 percent (table A-22). Ninety-nine percent of 

 the assigned ages were within plus or minus 1 

 year of the correct age. Reader A again had 

 the lowest error (table 38). 



A binomial test was used to determine if 

 the assigned ages were distributed equally 

 above and below the correct age. Reader A 

 had no significant bias for whole or sectioned 



'Reader A — A. Y. Roppel 

 Reader B — C. H. Fiscus 

 Reader C--H. Kajimura 

 Reader D — R. E. Anas 



38 



