EXPLANATION OF PLATE XX. 



Fig's 56 A and B. — Plethobasus aesopus (Green) 9, Des Moines R., 

 Dumas. 



Fig's 56 C and D. — Juvenile of P. aesopus. — Same locality as adult. 



Fig's 57 A and B.- — P. cooperianus (Lea) 9, Gascondy. 



Fig's 58 A and B. — Pleurohema obliquum pyramidatum (Lea) 9, 

 Osage R., Baker, Mo. 



Fig's 59 A and B. — P. catillus (Conrad) 9, Black R., Williamsville. 



Fig's 60 A and B. — P. coccineum (Conr.) 9, White R., Hollister. 



Fig's 61 A and B. — P. obliquum coccineum (Conr.) 9 , Osage R., Warsaw. 



Fig's 61 C and D. — Young P. obliquum coccineum (Conr.). — Same 

 locality as adult. 



Fig's 62 A and B. — P. obliquum catillus (Conr.) 9, Osage R., Colley's 

 Ford. 



Fig's 63 A and B. — P. Utterbacki Frierson (n. sp.) 9 , White R., Hollister. 



Fig's 63 C and D. — P. Utterbacki F. d", Jack's Fork of the Current R. 



