NATURE'S TRANSFORMATION AT PANAMA 



179 



it, it became so wild on my approach as 

 to prevent any further study ; but as this 

 particular monkey has not a prehensile 

 tail and the eyes and general features re- 

 semble the lemur, a strictly nocturnal ani- 

 mal, it is probable that it represents a 

 connecting link between the monkeys and 

 the lemurs. 



A HUNTER FOOLKD 



In the North I had found that the eyes 

 of one species of night-hawk, belonging 

 to the goatsucker family, would shine 

 brightly under the light. While at Gatun 

 I at once noticed that the night-hawks 

 circling about the electric lights after in- 

 sects had very brilliant eyes, and on one 

 occasion, when Mr. Anthony was in the 

 forest "headlighting'' for specimens of 

 the cat family, he saw a large pair of 

 brilliant red eyes glowing from the top 

 of a tree, and he fired with the expecta- 

 tion of getting an ocelot, or a similar ani- 

 mal. Instead of a heavy body crashing 

 through the branches there was a slight 

 swish, and in going under the tree he 

 found that he had killed a large goat- 

 sucker, the biggest of the night-hawk 

 family; and while he was disappointed, 

 the result of the shot showed that all the 

 members of these nocturnal birds possess 

 a tapetum. 



On other occasions we found that the 

 larger species of the southern Rodents, 

 like the agouti and paca, could be easily 

 shined at night, and since the northern 

 Rodents, with the exception of the rabbit 

 (which at best can be doubtfully classi- 

 fied as such), do not have shining eyes, it 

 is possible that this physical element may 

 be used as a basis for creating a sub- 

 order of Rodents. 



On the upper Chagres we found that 

 there was one species of fish which ap- 

 parently fed mostly at night, and under 

 the light its eyes would glow with the 

 same brilliant red possessed by the alli- 

 gator, another night feeder. While the 

 results in Panama enlarged the number 

 of species having reflecting eyes, they 

 confirmed more than ever the writer's 

 position, that the possession of the tape- 

 turn is directly associated with night vis- 

 ion, while the brilliancy of such reflec- 

 tion, it has been found, corresponds to 



the animal's need of such a faculty in 

 defense or aggression. 



NO PERIODICITY IN HABITS AS IN THE 

 NORTH 



The animal I felt a particular interest 

 in on this trip was the Central American 

 whitetail, a relative of the Virginia deer. 



This species and its geographic repre- 

 sentatives are found in all the lower Cana- 

 dian provinces, in practically all our 

 States and ranges southerly through Mex- 

 ico, Central America to the Andes, and 

 down into Brazil and Peru. The white- 

 tails are now, as in the past, the most 

 abundant and widely distributed of all 

 the groups of our native deer, and as far 

 as northern Mexico are represented by 

 several closely related forms, beyond 

 which they break into a number of dis- 

 tinct species. 



The northerly mating season covers a 

 period of about 30 days each fall ; the 

 bucks commence shedding their horns a 

 month or so afterward, while the fawns 

 are born in the late spring and within a 

 corresponding period of 30 days. Such 

 periodic and seasonable habits are un- 

 doubtedly caused and controlled by the 

 rigorous winters and lack of nourishing 

 food during the portion of the year when 

 any newly born offspring would suffer or 

 perish. Even in the Gulf States the mating 

 and breeding seasons correspond closely 

 with those of higher latitudes, due largely 

 to the northern origin of the species — with 

 the consequent inherited tendencies — and 

 also because, even in the most southerly 

 States, the colder winds affect many ten- 

 der varieties of vegetation. 



After passing the Mexican border, and 

 especially from Vera Cruz south, there is 

 a considerable enlargement of the breed- 

 ing season, since necessity no longer con- 

 trols the habits. 



A VARIABLE BREEDING SEASON 



On the Isthmus of Panama, with a 

 mean annual temperature of 80 degrees, 

 there is only an average difference of five 

 degrees between the so-called summer 

 and winter months, with the result that 

 the rut, the shedding of the horns, and 

 the birth of the young are very irregular. 

 On the Isthmus the fawns are born dur- 



