52 Proceedings of the Biological Society of Washington. 



enough, these 400-600 foot contours come where Merriam's Upper Austral 

 arm of the southern shore of Lake Ontario is about to merge into the 

 Transition zone ; and the appearance at Ithaca is a southern austral ex- 

 tension of the Ontarian arm of the Upper Austral zone. It seems reason- 

 able to prophesy that subsequent records in western New York will 

 doubtless come below the 600-700 foot contours. If this species then be 

 an Upper Austral form near the edge of the Transition zone we ought to 

 rind it at a higher altitude in North Carolina than in New York just as 

 Mr. Dunn recorded it. And, herein, we begin to get some sort of a key 

 to the apparent discontinuous records of this rare turtle. 



In the light of this distribution and what follows it seems decidedly 

 open to question whether or not the North Carolinian specimens should 

 be considered a new species, Clemmys nuchalis. 



Four characters enter into the diagnosis of this supposed new form and 

 are given as follows: "a longer nuchal plate, with the temporal blotch 

 forked ventrally, and the female, at least with a Matter and broader shell." 



Of the nuchal plate in these North Carolinian turtles we have the fol- 

 lowing: 



"The length of the nuchal plate ranges from 6 mm. to 7.1 mm. in the 

 female nuchalis, and from 4 mm. to 6 mm. in female muhlenbergi. It is 

 included in the length of carapace of female muhlenbergi from 13.6 to 16.4 

 times, and in that of female nuchalis from 12.7 to 13.2 times. No varia- 

 tion with age is apparent. 



"The one male (nuchalis) agrees in bodily proportions with male 

 muhlenbergi, — . 



"The nuchal plate of the one male is 8 mm. long. Nuchals of male 

 muhlenbergi range from 4.9 to 7 mm. in length. They are contained in 

 the carapace 12.8 to 19 times, while that of nuchalis is included 12.2 

 times." 



The nuchal plate in ten specimens varies in the males from 6 mm. to 8 

 mm. in length and from 2.5 mm. to 4.0 mm. in width, while in the females 

 it is from 5.5 mm. to 7.5 mm. in length and 3.0 mm. to 3.5 mm. in width. 

 The nuchal in the females is contained in the length of the carapace from 

 11.5 to 14.9 times; in the males, 12.3 to 14.8 times; and in a newly 

 hatched young, 13.6 times. Accordingly these female muhlenbergii are 

 more like the nuchalis diagnosed above and less like the muhlenbergi 

 there given. The newly hatched young has the nuchal almost square, 2.5 

 mm. long and 3.0 mm. wide, i. e., wider than long and yet at adulthood 

 the greater measurement comes in the length. The plate is quite variable 

 in this transformation to a long narrow plate and the relative changes 

 come in the width and not in the length of the plate. One of the adult 

 males has no nuchal plate and a cephalic prolongation of the first neural 

 replaces the obliterated nuchal. 



Of the length, width and height of carapaces of these two forms, C. 

 nuchalis and C. muhlenbergi, we have the following: 



" The range in length of carapace of C. nuchalis is in the females 79-93 

 mm., the male measuring 98 mm. 



