SERPENTS. 397 



of a most aggressive disposition, attacking without giving warning, aetually abound- 

 ing in its habitat, growing to a large size, and being of remarkable fecundity, probably 

 causes the death of more laborers in the sugar plantations of South America than any 

 other agent. Its venom is not spent in defence alone, but the fer-de lance being a 

 most voracious animal, it is of value in securing the rats and other small rodents 

 which would, were it not for this serpent, as well as several others, soon overrun and 

 destroy the cultivated districts. 



Under the generic name Caudisona appear those forms which resemble the true 

 Crotali, in that they are provided with the terminal rattle, but they show their 

 intermediate character in that the plates of the head are much like those of Ancistro- 

 don. The head is large and triangular and well shielded with frontal and parietal 

 ]>lates, the deep pit is present, but the rattles are but j)oorly developed and few in 

 number, being only capable of giving a feeble alarm. 



Caudisona tergemina., the black rattle-snake or raassasauga, is found in Ohio and 

 Michigan, and southward to Mississippi ; it has the scales in twenty-three or twenty- 

 five rows, a large pre-orbital, and a small and sul>triangular loreal. In coloring it is light 

 ashy brown or black on the back, depending on the exposure to which the animal has 

 been subjected ; those having lived in dry open localities seem to be bleached out. 

 The back is ornamented with seven rows of irregular spots. This animal is often 

 found in the l)urrows of the jirairie-dog, Cynomys ludovicianus. C. edwardsii is a 

 rare and a beautiful species inhabiting northern Mexico, Texas, and Arizona. The 

 scales are in twenty-three rows, the two outer rows being smooth. The geiieral color 

 is yellowish brown with several sei-iesof spots, the dorsal series numbering about forty- 

 two. The belly is light yellowish mottled with brown. C. miliaria is a very abundant 

 form in the south, where it ha.? received the name of ground rattle-snake, being fre- 

 quently found among dry leaves and in tangled grass, searching for small field-mice. 

 As it seldom gives any warning before taking the aggressive, it is very much dreaded, 

 especially by the common people, who regard it as even more dangerous than Crotaliis 

 horridus, but experiments show that its bite is not as virulent ; a cat which was 

 severely wounded, recovered at the end of a couple of days. Though the ground 

 rattle-snake has sufficient venom to kill the animals on which it preys, as the towbee 

 buntings, and field-mice, it has not, being but a small rej)tile, a sufficient quantity to 

 dangerously affect the larger animals. It has the scales arranged in twenty-one or 

 twenty-three rows, all but the outer keeled, and the labials numbering from ten to 

 twelve, the infralabials eight to thirteen. The coloring is generally dark, of an ashy- 

 brown shade, with a dorsal series of from thirty to forty irregular, band-like, black spots 

 with light edges, which become divided towards the tail. Along each flank and also 

 along the belly are three series of smaller spots alternately arranged. The greater 

 number of specimens have a dorsal line of a reddish color. The habitat is along the 

 southern states and Mexico. C. rava inhabits the tal)le-lands of jMexico, and is allied 

 to the previous species. It is of a yellowish color ornamented with from twenty-six 

 to thirty dee]) brown dorsal and an equal number of alternately arranged lateral spots. 

 The head is pale and immaculate, save a very minute p\iii(tulati<in. The sjiecies is 

 at present quite rare in museujns. 



The genus Crotalus has the parietal shields scale-like and the frontals either divided 

 or absent ; the tail is terminated by a well developed organ, popularly called the 

 rattle. Of this genus there are several species, which number some naturalists have 

 augmented by including the members of the previous Caudisona. As now restricted 



