310 Illinois State Lcihoratorij of Nntnral Jfistori/. 



Total length of a very large specimen t'rora Bluff Lake, 

 4() ; tail, 6.25. 



Shallow lakes and bayous of southern Illinois, abundant. 

 Bluff Lake, Union Co., Mt. Carmel (Ridgway). 



The water moccasin is very abundant in the lakes of the 

 southern part of the State. Mr. Ridgway of the National Mu- 

 seum states that it occurs as far north as Mt. Carmel, and thinks 

 possibly even to Vincennes. During July it may be seen in 

 great numbers coiled up on partly submerged logs, where it lies 

 for hours basking in the sun. If disturbed it hisses and vibrates 

 its tail after the manner of its relatives, the rattlesnakes, but 

 always retreats into the water when approached too closely. 

 Sometimes it makes its way up an inclined tree to a distance of 

 six or eight feet above the water, but tumbles headlong into 

 the water when alarmed. Mr. Peery, who lives at the edge of 

 Bluff Lake, in Union Co., tells me that in the fall of the year 

 this serpent leaves the water and resorts to the bluffs for hi- 

 bernation. A female kept in confinement by Mr. C. W. Butler, 

 of Anna, gave birth to young in the fall of the year. Dogs 

 are occasionally bitten by this species, but generally recover 

 after a spell of severe sickness. 



All the Illinois examples of the species belong to the va- 

 riety pismm-KS. The variety piicinax may be known from 

 the position of its second labial, this plate being crowded up- 

 ward from the margin of the jaw. It has not been observed 

 within our limits. 



CLASS AMPHIBIA. 



Exoskeleton generally wanting. Two occipital condyles. 

 Mandible of several pieces. No true diaphragm. Respiration 

 during a part or whole of life by means of branchiic. Heart 

 in the adult with three chambers. Two aortic arches. l>lood 

 not warm, red corpuscles nucleated. Alimentary canal termi- 

 nating in a cloaca. Oviparous. 



Illinois members of the group belong to the two orders 

 characterized below. Our species all have naked skins. A 

 group (order Gyranophiona) represented by a few genera occur- 



