182 



NEW YORK STATE MUSEUM 



Body very convex and smooth, capable of being rolled into a 

 round ball. Uropoda long and pointed. 



This species, like Armadilliclium, has the habit of rolling itself 

 into a ball when handled or disturbed, and they have thus obtained 

 the name pill-bugs. From Armadillidium it differs in having long 

 and pointed uropoda. From the rest of the Oniscoidea it differs in 

 its convex and more elongated form and its ability to form a ball. 

 The body also lacks the tubercles usually found in the genus 

 Porcellio. 



Length 10-12 mm. Color chocolate brown or dark gray with a 

 submarginal row of white spots, within which is a large mass of 

 smaller, irregular markings. No median stripe. The markings of 

 this species are fairly constant. 



It is rather rapid in its movements, running off and hiding under 

 any sheltering object. If handled it rolls itself up into a very per- 

 fect ball and is difficult to distinguish from pebbles. Found in 



woods under logs or along 

 roads under stones, usually in 

 rather dry situations. 



Common all over the city. 



Porcellio rathkei Brandt 



Porcellio rathkei Brandt. 

 Bui. de la Soc. Imp. d. Naturalistes 

 de Moscou 1833. 6:15. Sars. /. c. 

 1899. 2:180, pi. 79. Richardson. /. c. 

 1901. p.567. 



Joints of flagellum of anten- 

 nae subequal, color variable but 

 usually with median and lateral 

 stripes. 



The commonest as well as the 

 most variable of our terrestrial 

 Isopoda. In form it is only 

 moderately convex, and the 

 small tubercles. The front is 

 smoothly rounded, and the uropoda are moderately long. 



Figf- 55 Porcellio rathkei 



dorsal surface is covered with 



