1 



1912. J NATURAL SCIENCES OF PHILADELPHIA. 457 



to one of the slides, and in this position was passed through the 

 various grades of alcohol and cleared and mounted. In a few species 

 the active movements of the body may be inhibited to a considerable 

 degree by allowing them to remain for some time in sea water held 

 in small vessels, but in the greater number of cases the resulting 

 sluggishness is accompanied by an abnormal distortion of the body 

 that is difficult to overcome. Chloretone (aceto-chloroform) and 

 a number of other narcotizing agents were used from time to time, 

 but without much success, since the animals, even while compara- 

 tively active, would undergo a surprising degree of disassociation of 

 the tissues. Delafield's hematoxylin was usually employed as a 

 stain, occasionally with Orange G or rubin, and after such treatment 

 the specimens were generally examined in clove oil and finally 

 mounted in balsam. 



Key to California. Species. 



I. Without sucking disc on ventral surface Tribe Acotylea. 



A. Nuchal tentacles present Family Planocerid^e. 



a. Pharynx almost wholly in middle half of body; antrum- 

 masculinum continued close to dorsal surface as a 

 crescent-shaped blind sac; accessory sac 3-parted, 



Planocera calif ornica. 

 aa. Pharynx nearly central; antrum-mascujinum normal: ac- 

 cessory sac normal, 

 b. Nuchal tentacles at beginning of second fourth of 

 body; ample pharynx with large deep folds; sex 

 openings rather close to posterior border of pharyn- 

 geal pocket Planocera burchami. 



bb. Nuchal tentacles before end of first fifth of body; 

 pharynx small and weakly folded; gut branches 

 anastomosing; *sex openings far removed from 

 pharyngeal pocket and from posterior end of body, 



Stijloehopla na calif ornica . 



AA. Nuchal tentacles wanting Family Leptoplanid^e. 



a. A single seminal vesicle Genus Leptoplana. 



b. Separate sex openings. 



c. Vasa deferentia anastomosing L. rupicola. 



cc. Vasa deferentia unbranched; gut branches anas- 

 tomosing, 

 d. Pharynx central, deeply lobed; penis broad, 

 blunt; accessory sac lying wholly behind 



the female opening L. timida. 



dd. Pharynx considerably nearer the posterior end, 

 weakly folded; penis very long, attenuate; 

 accessory sac lying wholly before the female 

 opening : L. saxicola. 



