386 REPORT OF NATIONAL MUSEUM, 1893. 



Georgetown, Demerara, consequently in a tropical climate and the 

 home of the snakes, mnst be said to have had even superior advantages. 

 In a very interesting paper published in "Timehri,"* of which be is 

 editor, he gives as his experience that the sloughing, or exuviation, of 

 the general skin and that of the terminal button, or cap, of the tail 

 forming the new rattle Joint take place at the same time and are part 

 of the same process. It is consequently possible that Feoktistow's 

 results may have been caused by irregularities of the sloughing process, 

 due to tlie captivity. Out of twenty-four specimens bred in a cage in 

 the museum, Mr. Quelch brought two up on mice till they reached a 

 length of more than 3 feet, when the paper was written. Here is an 

 abstract of his account relating to these specimens: 



At birth they were from 9-10 inches in length and i to | inch thick, and like the 

 other 22 of the set possessed but a terminal, elongated, horny, stump, though under 

 the termination of the scales an anterior piece was to be observed. Now, 16 months 

 after, they are more than two feet in length and more than an inch thick — one, 

 which has throughout been the more voracious, being somewhat longer and thicker 

 than the other — and the larger one possesses a rattle of four separable links, while 

 the other has six of these, but the individual links considerably smaller than those 

 of its brother. In the case of the smaller snake, with sis pieces in the rattle, these 

 corresi)ond with each exuviation, the rattle being perfect, and bearing the terminal 

 elongated stump with which it was born. In the other, with four, three terminal 

 links have been lost, these having been detached during its sixth exuviation. 

 During 16 months, therefore, the one has had seven exuviations, and the other and 

 smaller but six. 



In a later note, supplementary to the above {op. cit, pp. 170-171), Mr. 

 Quelch adds the following: 



Since writing the foregoing paper it has been possible, from actual observation of 

 these young forms, to trace the development of the rings still further. On February 

 5th the larger of the two young specimens was about 2A feet in length and possessed 

 four rattle rings. Since then two exuviations have taken place, one on Wednesday, 

 March 2.5th, when an extra ring was added to the rattle, thus making five; and 

 again, about two months after, on May 27th, when the sixth ring was added. In 

 the case of the smaller snake, whicii on February 5th was about 1| feet in length, 

 two exuviations have also taken place, at intervals also of about two months between 

 each exuviation. On February 28th an extra ring was added by change of skin; 

 and again on May 4th, when 8 rattles were registered in total number. It is note- 

 worthy that in the larger specimen of these two young ones there are only six 

 rings, tliree having been lost in early changes, while in thesmaller specimen there are 

 eight, the total number from birth being retained, as shown by the presence of the 

 original terminal button with which they were born. The larger specimen is now 

 (.lune 11th) about 3i feet in length, while the smaller is about 2f feet. During early 

 life these vipers are thus, with free diet, observed to exuviate and thus add to the 

 rings of the rattles every two months. 



Dr. Feoktistow, where he speaks of rattles with from 15 to 18 joints 

 as being rare, adds in a footnote that " rattles of 42 joints, as figured 

 by Seba, surely exist only in the imagination." There is said, however, 

 to be a later account and figure of a rattle of no less than 44 joints, 



* The Rattlesnake. — The Growth of the Rattle. Timehri (n. s.), v, pt. 1, June, 

 1891, })p. 1-11-f-plate. 



