the Notophthalmus viridescens is found at a lake two miles north of Ann 

 Arbor, and the Crotalophorus tergeminus occurs as a rule only in 

 marshes and low places, differing in this respect very strikingly from 

 the rattlesnake of the East. 



The habits of some of our animals are met by corresponding 

 modifications of structure. A remarkable instance of this is seen in 

 the soffc-shelled turtles, Trionychidce. In these there is a prolongation 

 of the nostrils forwards by a fleshy or leathery tube. , The significance 

 and utility of this can be readily understood by recalling the fact that 

 these animals hve buried in mud, under water, thus rendering a hard 

 shell unnecessary for protection, and that respiration is accomplished 

 by their bringing this proboscis to the surface. The peculiar modifi- 

 cation of the rostral shield in the hog-nosed snake, Heterodon, is 

 probably useful to the animal in removing the earth into which it 

 burrows or digs for food. All modifications can be readily understood 

 when the habits of the 'animal are knoivn, just as surely a's we can see 

 the adaptability of the foot-pads in the geckos which enable those 

 animals to walk upon the ceiling. 



It maiy be well to state also that our species of gairter-snake — 

 Uutcenia sirtalis — shows marked variations, some individuals being 

 without the dorsal stripe, some having the colors bright, others dull, 

 while some have the sides spotted and others are uniform with the ex- 

 ception of the stripes. Our Eumeces fasdatus also varies greatly, the 

 young being bright, with the stripes welP marked, while the adult is a 

 uniform dark green or olive. Of our Graptemys geograpMca, a speci- 

 men was recently found by me upon the Huron river, of which the 

 shell exactly resembled the G. LeSueurii, but the other parts of the 

 animal conformed precisely to the type. 



The blue racer of the West; also differs strikingly in color from the 

 typical Bascanion constrictor. Our animal is not black, but varies from 

 a light azure blue to a bluish black, in ftiost instances being of the 

 fortiier color. The ordinary shade of the adult Michigan animal is light 

 azure blue, and it might properly be designated as a distinct variety, 

 under the term of cceruleus. , " 



A very troublesome thing in regard to the study of these animals is 

 the change that their colors undergo in alcohol. Thus, yellow becomes 

 white; green, blue; and red, brownish black ; while brown and metallic 

 tints remain for some time imchanged. However, exposure to the sun 

 for a season will often enable one to form an idea of the original shade. 



Sex is often also a difficult matter to determine without dissection. 

 Nevertheless, in most, if not all turtles, the male may be recognized by 

 its concave plastron. In the Jnoura, the vocal vesicle when present 



