182 Proceedings of the 



266 in the body and tail, inclusive of the conical scale which 

 terminates the tail. Counting the scales from the under side, 

 there were in all 278, or five more, the excess being in the lower 

 jaw. From the margin of the lower jaw to the verging scales 

 of the cloaca there were 137, and from this to the point of the 

 tail, 141. 



The valve of the cloaca, situated near the middle of the 

 body, produces no interruption of the symmetry, or of a con- 

 tinuous declination; and, indeed, it would be difficult of detec- 

 tion by those who are unacquainted with the structure of ser- 

 pents. It is a semilunar flap, so to speak, opening trans- 

 versely, two scales deep, and fringed by six scales, which are 

 adjusted very perfectly to the scales of the tail. A reflection of 

 the cuticular tissue lines this flap, forming on the upper or 

 body side distinct minute scales, merging in a highly elastic 

 network-like structure, which surrounds the cloacal aper- 

 ture, and is attached below to the marginal scales of the flap. 

 This reflected portion of the scales is always thrown off as 

 part of the slough, and is seen as a sort of pouch in prepared 

 sloughs. 



The colours of the animal are derived essentially more from 

 a sort of pigment which covers the scale-plates than from the 

 scales themselves ; still, most sloughs have faint brown streaks 

 on the back scales, and the side ones are sometimes tinged 

 of a slight dusky hue ; but the scales of the belly, which look 

 dark when in connection with the animal, are always colour- 

 less when detached from the body. 



The scales and scale-plates are arranged in rows disposed 

 backward from the centre line of the back in an angular 

 manner. There are, however, instances of imperfect rows — a 

 sort of indentation of a partial row, as if to meet some require- 

 ment of contour or function. 



The rows are, as a rule, of equal numbers, from 28 in the 

 neck to 2 in the tail ; but in every animal there are a few un- 

 equal rows, and the tail ends with a single conical scale. 



The scales in the upper jaw number 160 

 In the under jaw ... ... 117 



277- 



