350 R. J. GOSS 



Pudella mephistophelis of the mountains of Ecuador and Peru, and 

 Fiidii piuhi of the Chilean Andes) is unfortunately not axailable. 



At the equator the lengths of da\ and night are essentially un- 

 altered and equal throughout the year, and the annual fluctuations 

 for some distance on either side of the equator are too insignificant 

 to be of biological importance. Therefore, it is not possible for deer 

 to exhibit annual cycles governed by seasonal variations in dav 

 length. Presumably this explains why the members of some tropical 

 species of deer sometimes retain their antlers for periods longer 

 than one year. The earliest account of such an interesting phenom- 

 enon was by Forsyth (1889), who wrote (pp. 234-235), "I have 

 taken much pains to assure myself of a fact, of which I am now per- 

 fectly convinced, namely, that neither in the case of the sambar nor 

 the spotted deer . . . are the antlers regularly shed every vear in 

 the Central Indian forests." Indeed, individual stags were observed 

 not to shed their antlers for successive years in the same localitv. 

 With regard to the sambar and the chital, or axis deer, of Ceylon, 

 Phillips ( 1927-1928 ) reported that the antlers are renewed annu- 

 ally (though not in unison) for the first few vears of life, but there- 

 after they are shed at variable seasons and may occasionally' per- 

 sist for several years without being replaced. Similarly, Cabrera and 

 Yepes (1940) reported that in the red brocket of tropical South 

 America the antlers may sometimes last more than a year. Finally, 

 Pocock ( 1912 ) mentions a South American deer identified as 

 Mazama bricenii, which was observed in captivity in England to 

 shed its antlers in April of 1908 and 1909 but not again until May 

 1911, a period of 25 months having elapsed. Thus, there appears to 

 be sufficient evidence to support the contention that the members of 

 some species of tropical deer mav retain their antlers for unusuallv 

 prolonged periods of time, though the\' also possess a strong in- 

 clination to shed their antlers annuallv. In the latter cases, however, 

 one wonders how an annual rhythm might be established and 

 maintained in the absence of seasonal diurnal variations. Although 

 it seems doubtful whether animals could recognize and respond to 

 seasonal modifications in the declination of the sun, such meteoro- 

 logical conditions as rainy versus drv seasons suggest themselves as 

 an obvious answer, but experimental proof of this is lacking. Alter- 



