ABT. 11 NORTH AMERICAN TADPOLES — WRIGHT 41 



unlike Rana clamitans, which is more or less uniform. When a tad- 

 pole has hind legs well developed (forelegs not out) back becomes 

 bluish black and the hind legs stand out by color contrast by being 

 a prominent citrine, buffy citrine, dull citrine, or olive citrine. When 

 it reaches the four-legged stage the spots of the posterior back are quite 

 well outlined. The mental region is grayish olive and more or less 

 clouded. The pectoral region has a little of greenish color. Where 

 the sides join the belly the body is mottled. Belly straw yellow, 

 colonial buff, or deep colonial buff. 



Tail. — On the lower crest along its edge are many roundish cartridge 

 buff or pinldsh buff spots. On the base of the musculature of the 

 tail these collect as pinkish cinnamon spots suggesting somewhat the 

 light area in a similar place on Rana grylio tadpoles. On the rim of 

 the dorsal crest some of the cartridge buff spots are almost whitish. 

 There are very few black specks on the tail in mature tadpoles. A 

 little later the crests have prominent black spots on posterior half of 

 the tail. In two legged tadpoles a black blotch or blotches appear 

 with pinkish cinnamon spots at the base of the tail and these are very 

 prominent. 



Iris black and pinkish cinnamon. 



Some tadpoles one month old had on the dorsum three pairs of 

 black or dark spots: One on each nostril; one on or near each eye; 

 and one on each side of the middle of the back. The dark of each 

 eye connected with the back spot by an arc or semicircle of Hght 

 color. This is the general appearance without a lens. 



General appearance. — Tadpole large (99 mm.) of the R. grylio or 

 R. clamitans type, but without black gular area of R. grylio. Venter 

 heavily pigmented with white so intestine do not show through in 

 life or preserved specimens. Tail elongate, tip acute. Dorsal crest 

 not as wide as musculature, not extending forw^ard on body much 

 beyond the level of the buds of the hind legs. Spiracle sinistral, 

 directed backward and obUquely upward, just visible from dorsal 

 aspect. Spiracular opening just touches lateral axis as in R. grylio. 

 Eye just above or rarely on lateral axis. Anus dextral on level with 

 lower edge of ventral crest. Muciferous crypts distinct. A short 

 dorsal row of 8 to 10 pores on either side of middle line of back from 

 the dorsal crest forward; from above the middle line of insertion of 

 tail musculature on body to back of eye is a distinct line of pores. 

 Just before it approaches the eye area it sends obliquely upward and 

 backward toward dorsum a short line in the direction of the end of 

 the first row described. When this main line reaches area just back 

 of the eye, a blind short line starts transversely across occiput but is 

 very short, another continues as supraorbital line to above nostril, 



