H4 



P. B. SIVICKIS. 



Material: Description of Species. 



In many rivers and lakes about Chicago a planarian, commonly 

 identified in the past as P. maculata, occurs in large numbers. 

 Even a cursory examination makes it evident that this form differs 

 in various respects from P. maculata of the Atlantic slope. Atten- 

 tion has already been called to these differences by Hyman ('20). 

 A comparison of living individuals of this form and P. maculata 

 from the region of Woods Hole, Mass., shows the following differ- 

 ences: The pigment pattern of the mid-western form (Fig. 1) is 

 distinctly coarser and more irregular ; the individual pigment spots 

 and the unpigmented areas are more clearly visible to the naked 

 eye than in P. maculata (Fig. 2). In a mixed stock the two 







I 



W'? :; 



Fig. 1. Planaria lata n. sp. 

 Fig. 2. Planaria maculata. 



