PEACH. ROOT SPECIES OF POItCELLIO. 121 



a. d rsalis. The space between the rows of yellow spots of a deeper black 

 color than other parts of the body, forming a black broad stripe along the mid- 

 dle of the back. This stripe is much more obvious in the living specimen than 

 after death. 



b. mulligutlatus. A row of smaller whitish spots along ihe middle of the 

 back between the yellow ones. Common. 



c. marginatus. The hind margins of the segments pale or whitish. 



d. lateralis. The outer fourth part of each segment whitish with a black 

 spot therein. 



e. limba is. The spots of var. d confluent forming a black stripe with a 

 brown or blackish spot on each side of each segment outside of the stripe. 



It is difficult, in short, to find two individuals of this species which are alike 

 in every respect. Still, the species is in all instances readily distinguished by 

 its sculpture, the raised granules occupying the hind margins of the segments 

 although they are less elevated here than upon the disk. In all our other spe- 

 cies having the surface granulated, these margins are smooth. 



The Hough Porcellio (P. scaler, Latreille). Blackish lead-colored often 

 varied with irregular blotches of whitish, the surface rough from numerous 

 elevated points which are arranged in irregular transverse rows. Length 0.45. 

 This is much more rough and the elevated points more acute than in either of 

 the foregoing species. I have not met with it in this State. Specimens sent 

 me from Ohio by Dr. Robert H. Mack, and from Illinois by R. W. Kennicott, 

 differ in no respect that I am able to perceive from European individuals of this 

 species. 



