N 



Explanation of Plate I. 



Fig. 1. General appearance of Polycclis tibetica from a preserved specimen. ;//, mouth; 

 gp, genital pore. 



Fig. la. Sketch of heail of living specimen from lot K 66. (G. E. H.) 



Figs. 2, 3. Ej-e number and arrangement of small specimens from lut K 77. 



Fig. 4. Eye number antl arrangement of large specimen from lot K 76. 



Fig. 5. Large specimen from lot L21 having the best extension of auricles found. 



Fig. 6. Large specimen from lut K 66 with head probably regenerating, showing few eyes. 



P'ig. 7. Sagittal section of the copulatory apparatus of the ripest specimen, from L 25. be, 

 bursa copulatri.x ; bs, bursa stalk; (V, common oviduct ; ^^'/i, genital pore ; iini, 

 male atrium: Z^. i)enis; /ifc, jicnis bulb. 



Fig. 8. Transverse section nf second specimen from L 25, taken tln'nugji the center of the 

 ])enis bulb, bs, bursa stalk: o, oviduct; />/'. penis bulli; ;■(/, vas deferens. 



