EXTERNAL CHARACTERS 7 



toe, the prehallux, on the inner side. The first two 

 toes each have three joints, the next two have four, 

 and the fifth, five. The toes arc joined by a web. 

 How far docs it extend on each toe? 



11. The dermal plicae are folds extending caudad from 

 the eyes. How many are there, and how far can you 

 trace them on your specimen? 



12. The vent or cloacal aperture is mesial and dorsal 

 to the hind legs. 



Study the pigmentation. What colors are found, and 

 where? What is the size, shape, and pattern of the spots? 

 Both pigmentation and pattern are especially important in 

 R. pipiens. 



Make the following measurements, in millimeters: 



a) from snout to vent; 



b) head, length; 



c) head, width; 



d) snout; 



e) eye; 



f) width between eyes; 



g) tympanum; 



h) forelimb, and subdivisions; 

 i) hindlimb, and subdivisions. 



Drawing 1. Draw the dorsal view, the head towards 

 the upper edge of the sheet, natural size (xl)} 



* Bullfrog (x%). 



