2 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



from Alaska. The second species, of which only two specimens are 

 available, one sexual and the other asexual, is a dendrocoelid. A 

 series of sections of these animals showed that this is an undescribed 

 species of the genus Dendrocoelopsis Kenk, 1930. 



The 1962 material of the Lake Tahoe planarians was sent first by 

 the collector for identification to Dr. L. H. Hyman of the American 

 Museum of Natural History. It was, however, returned to me by 

 Dr. Hyman herself, who told me that her declining health did not 

 permit her to continue taxonomic work. The 1963 material was pre- 

 sented to me by Mr. Frantz upon my request. He also provided me 

 with the detailed data of collections of the Lake Tahoe bottom samples, 

 some notes on living material, and several publications about the lake. 



I wish to express my hearty thanks to Dr. Libbie H. Hyman not only 

 for giving me the rare opportunity of studying these valuable materials 

 but also for kindly permitting me to continue her excellent serial work 

 "North American Triclad Turbellaria" (see "References"). She also 

 gave me much valuable criticism. I am indebted to Mr. Ted C 

 Frantz and his co-workers (Messrs. A. J. Cordone, D. Weidlein, S. 

 Davis, R. Wickwire, S. Nicola, J. Curran, N. Saake, R. Hauswald, 

 V. Keefer, M. Arnold, and B. Zorko) for the gift of the present collec- 

 tions. I owe much to Dr. Roman Kenk and to Professor Atsuhiko 

 Ichikawa for their interest in the work and to Dr. Marie M. Jenkins 

 for some pertinent literature and for correction of my English 

 manuscript. 



This paper is affectionately dedicated to Dr. Libbie Henrietta 

 Hyman, an old specialist of turbellaiians. 



Abbreviations used in figures. — bc=bulbar cavity; bs=bursa 

 stalk; cb=copulatory bursa; ca=common antrum; cg=cement 

 glands; cod=common ovovitelline duct; e=eye; ed=ejaculatory duct; 

 gp— genital pore; i=intestine; ia=intestinal anastomosis; m=mouth; 

 ma=male antrum; o=ovary; od= ovovitelline duct; pb=penis bulb; 

 pg== penis glands; ph= pharynx; pp= penis papilla; sd= sperm duct; 

 sv=spermiducal vesicle; t= testis; v= vagina; yg=yolk gland. 



List of localities. — The original vial numbers were rearranged 

 according to the division of counties and states of the localities (see 

 fig. 1). Stations 1-24 are located in California in the western two- 

 thirds of the lake area; 25-40 are located in Nevada in the eastern 

 third of the lake area. The number following each station number 

 indicates the specimen lot number as it was registered in my fixing 

 notebook. The information following this number is the data found 

 on the labels of the vials, together with my own notes made from 

 examination of the specimens. Four lots of specimens (nos. 5, 23, 30, 

 32) that I received from Dr. Hyman were already dry. 



