3S« 



FRESH-WATER BIOLOGY 



97 (98) Color gray Planaria velata Stringer 1909. 



Ixngth of mature specimens 15 mm. Color of dorsal side to unaided eye varies from almost 

 white to a very dark gray almost black. Under lens, a colorless groundwork with black pig- 

 ment granules extremely variable in number. Much lighter in front of eyes and over cephalic 

 appendages. Lighter on ventral surface, over pharynx, and near lateral margins. Preserved 

 material often appears colorless and oval in shape. Encystment of the entire animal or divi- 

 sion into a variable number of pieces followed by encystment of the pieces occurs in response 

 to unfavorable conditions. The cysts resemble egg cocoons in appearance and are provided 

 with a shell. CiUa conspicuous. Crete and Omaha, Neb. 



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Fig. 634. Planaria iielata iromlUe. X 12. (After Stringer.) 



98 (97) Color brownish-red mottled with purpHsh dots except at margins. 



Planaria unionicola Woodworth 1897. 



Length of the one specimen (preserved) from which the description was made 2.8 mm., 

 breadth 1.8 mm. Probably 8 to lo mm. long when alive and extended. Purple dots occur 

 in masses. Red color absent over an elongated posterior median area extending nearly to the 

 posterior axis of the animal. Appearance of posterior end suggests an 

 injury or transverse division. Color of alcoholic material a deep rusty 

 red. Found creeping on the mantle of Unio alatus in IlUnois River. 



Fig. 635. Planaria unionicola from life. About X 3. (After Woodworth.) 



99 (96) Margin of anterior end uniformly curved, not sinuous. Color white. 



Planaria truncata Leidy 1851. 



Length lo to 12 mm. Thickness slight. Translucent. Digestive tract variously colored 

 by food. Two crescent-shaped eyes situated far back and near together. Pharynx much 

 elongated and central in position in sexually mature specimens. Intestine with Uttle anas- 

 tomosis of branches. Ovaries two, sometimes 

 lobed. Testes many. Uterus large with stalk 

 running to left side, dorsal to vasa deferentia and 

 oviducts and entering atrium laterally. Asexual 

 reproduction by fission. Small stream Bryn Mawr 

 campus; rivulet at Newark, Delaware. 



A comparison of descriptions of P. truncaia 

 Leidy and P. morgani Stevens and Boring leaves 

 but little doubt that they are identical. The 

 blackish- white color mentioned by Leidy evidently 

 was due to food contained in the digestive tract 

 and not to body pigment since the margin is de- 

 scribed as translucent. 



Fig. 636. Planaria truncata. (A) From life. X 4- (5) 

 Dorsal view of sexual organs; a, atrium; c, cirrus; g^, 

 genital pore; od, oviduct; ph, pharynx; /, testes; u. 

 uterus; w, vas deferens. X 7. (After Stevens.) 



100 (95) Anterior end rounded in preserved condition (Uving condition not 

 known). . . Planaria simplex Woodworth 1897. 



Length 4 mm., greatest diameter 1.8 mm. Color of alcoholic specimen ochef-yellow. Pig- 

 ment located in spots of nearly uniform size, distributed uniformly over all parts of the body; 

 no clear areas surrounding eyes or at sides of head. General shape ovate. Broadest at one- 

 fifth the total length from the anterior end, tapering from here to rounded posterior extremity. 

 Anterior «nd rounded, set off from the rest of the body by sUght lateral indentions at the level of 

 the eyes. No evidence of cephaUc appendages. Mouth one-third of total length from posterior 



