422 PROCEEDINGS OF THE ACADEMY OF [Sept., 



above description, I judge that the animal was very probably a speci- 

 men of the lady turtle, Chrysemys marginata (Agassiz). Dr. De Verter 

 informed the writer that when kept in an aquarium and fed, each head 

 acted wholly independently of the other, the two being thrust forth 

 for different articles of food — meat, mosquito larvae, tadpoles, etc. — at 

 the same time or at intervals, as occasion and opportunity demanded. 

 Wliat finally became of the specimen on the death of Prof. Collett is 

 not known. 



Five-legged Frog. — In the spring of 1892, while teaching zoology at 

 Terre Haute, I heard several times of a five-legged frog at a greenhouse 

 in that city. I finally visited the place, but the specimen could not be 

 located. The proprietor informed me that lie had seen it on a number 

 of occasions, and had caught it once and then let it go. According to 

 his description, it was probably a specimen of the leopard frog, Rana 

 virescens Kalm, with a fifth leg of the same size as each of the two 

 front ones, which was joined to the left side about an inch back of and 

 a little higher than the normal front leg. The specimen was not seen 

 after my visit and probably fell a victim to some prowling cat. 



Two-tailed Salamander. — On June 21, 1906, I took from an ancient 

 shell mound which was being excavated near Shoals, Martin county, 

 a small specimen of the ashy salamander, Plethodon cinereus (Green), 

 which possesses a forked tail. The animal itself was only 38 mm. in 

 length, the tail comprising 12 mm., or nearly one-third. At a point 

 near the middle the tail forked, the two prongs being separated in life 

 by an angle of about 30 degrees. The left or longer fork was 7 mm. in 

 length, while the right or shorter one was but 5 mm. long. Instead of 

 being cylindrical as in typical specimens, each portion was flattened, 

 with rather sharp edges above and below. 



It is very probable that cases of malformation among reptiles and 

 batrachians are much more common than is generally supposed. It 

 is safe to say that not more than ten per cent, of the normal individuals 

 which are born or hatched ever come within the range of man's vision. 

 The great majority of the malformed ones are, like those of the 

 domestic animals, either still-born or short-lived. The number of 

 specimens of ' ' freaks ' ' which come to the notice of man is, therefore, 

 doubtless a very small per cent, of those which actually occur. 



To the factor of natural variation,. rather than that of "shock," is 

 probably due the malformations which do occur. If but three speci- 

 mens out of 120 of one brood of snakes were malformed on account of 

 a shock to the pregnant mother, why did not that shock affect the 

 others? 



