THE PYTHONS AND BOAS 2553 



in a tree this snake will often dart down its head from a considerable height to 

 seize a passing peccary or other animal. Bates tells us that the anaconda will 

 occasionally seize human beings, and this statement is fully confirmed by other ob- 

 servers. In Brazil, where water is abundant throughout the year, this snake is 

 active at all seasons, although it is stated to display the most activity during the 

 hot months of December, January, and February. In other districts, however, ac- 

 cording to Humboldt, during the dry season, it is in the habit of burying itself deep 

 in the mud of the dried-up rivers, where it is sometimes disinterred by the natives 

 in a torpid condition. Very little is known with regard to the breeding habits of 

 the anaconda. Since, however, females have several times been killed, containing 

 eggs with embryos far advanced inside them, it would seem that the young are born 

 alive. When they first make their appearance in the world, the young are reported 

 to take to the water, although they soon leave it to pass a large portion of their 

 time in trees. 



L,ong supposed to be exclusively a tropical and South-American 

 group, the true boas are common to the hotter regions of America and 

 Madagascar. From the anaconda, the boas may be distinguished by the whole of 

 the nasal shields being separated in the middle line by small scales. The body may 

 be either cylindrical or slightly compressed, and the short and more or less prehen- 

 sile tail may have either the whole or a portion of the shields on its lower surface 

 arranged in a single series. In America the genus is represented by five species, 

 two of which range as far south as the inland districts of upper Argentina. All 

 species are characterized by having the loreal region of the head covered either with 

 a single small shield or with small scales, and by the number of rows of shields on 

 the under surface of the tail ranging from forty-five to sixty-nine. On the 

 other hand, in the Malagasy boas (Boa madagascariensis and dumerili] there 

 are several shields on the same region of the head, while the number of rows of 

 shields beneath the tail is only from twenty to forty-one. The best-known repre- 

 sentative of the genus is the common boa, or boa constrictor (B. constrictor), which 

 ranges in South America from Venezuela to upper Argentina. At times reaching 

 as much as twelve feet in length, it has the muzzle slightly prominent in the adult, 

 although obliquely truncated in the immature state. In general color it is pale 

 brown on the upper parts, with from fifteen to twenty dark brown crossbars, which 

 expand inferiorly, sometimes to such an extent as to become connected on the sides 

 of the body, and thus to surround oval or elliptical spots of the light ground 

 color; the expanded portion of each bar having a light longitudinal line. On 

 the sides are a series of large light-centred dark brown spots, most of which 

 alternate with the crossbars; and on the tair all the markings become relatively 

 larger of a brick-red color, margined with black, and separated by yellowish in- 

 tervals. From the muzzle to the nape runs a dark brown median streak, widening 

 posteriorly, where it may be looped; another bar of the same color passes on each 

 s-ide of the head through the eye, while there is a tkird below the latter, and the 

 lips are marked by such bars; the rostral shield of the snout being also ornamented 

 with a crescentic blackish mark. The under parts are yellowish, with spots and 

 dots, or merely dots, of black. The whole tone of coloration is dull, sombre, and 



