52 



ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 39 



Amphipoda These humpbacked, many-legged animals, 



Small Water fig. 57, are also crustaceans, but unlike the 



Shrimps isopods they are flattened sideways like a 



flea. They are all aquatic but are seldom 



found swimming in open water; they prefer to live in tangled 



masses of vegetation, under stones or logs, and among debris 



in the very shallow water where 



it touches the bank. These little 



shrimps are never more than 



about one-half an inch long and 



are frequently collected in large 



numbers along with aquatic 



beetles. 



Fig. 57. — Amphipoda. Gammarus 

 sp., a common small water shrimp. 

 Actual length 0.4 inch. 



Pseudoscorpionida The pseudoscorpions, which belong to the 

 Pseudoscorpions spider group, are characterized by a pair of 

 stout pinchers at the end of the front legs, 

 as in Larca granulata (Banks), fig. 58. They have short, stout 

 bodies, each with five pairs of legs includ- 

 ing the chelate front pair, but unlike the 

 true scorpions they have no tails or 

 stings. The pseudoscorpions are some- 

 times found indoors in old books, looking 

 for their prey of 



small insects. They 

 occur in greater 

 numbers in wood- 

 ed areas. 



Fig. 58. — Pseudoscor- 

 pionida, Larca granu- 

 lata, a native Illinois 

 pseudoscorpion. Actual 

 length 0.1 inch. 



Phalangida Spider-like forms, each animal with a short, 



Daddy Longlegs, round body and four pairs of walking legs 



Harvestmen that in most species are very long, fig. 59. 



They occur 



chiefly in woods and may be 



found in numbers walking over 



foliage, logs, and bluffs. They 



Fig. 59. — Phalangida. A common 

 harvestman or daddy longlegs. Ac- 

 tual length of body 0.3 inch. 



