PHILIPPINE POLYCLAD TURBELLARIANS. 649 



trunk and end blindly in the parenchyma just beneath the basement 

 membrane. 



The genital organs, though difficult to observe owing to a poor state 

 of preparation, seem to be constructed on a plan similar to those 

 figured by Von Plehn 8 for Diplopharyngeata filiformis, a species 

 from Sumatra. Just behind the pharynx lie the male organs, in 

 which no seminal vesicle nor prostate of any kind could be detected 

 in the sections available. 



The female gonopore is situated nearly at the middle of the body 

 and leads into an irregular antrum, which in turn appears to connect 

 with the vagina. 



In spite of fundamental similarity in the structure of the genital 

 organs and also of the absence of the ventral sucker, the present 

 species appears to be somewhat related to Plehn's D. filiformis, just 

 mentioned, but is distinctly at variance from this in some respects. 

 D. filiformis is wholly devoid of any trace of tentacles, has the 

 pharynx reduplicated, and presents no anastomasing system of the 

 intestine. For the present I can not feel certain of referring the 

 present example to any previously recorded genus. 



As to its systematic position I am not in a position to make any 

 assertion, because the specimen is too incomplete to admit of a satis- 

 factory diagnosis. I feel, however, justified in not ranging this re- 

 markable form either under the Pseudoceridae or under the Eury- 

 leptidae, chiefly on account of appearing devoid of prostate and 

 sucking disk of any kind, not to speak of other points of differences. 

 Provisionally it may be placed under the Diplopharyngeatidae. 

 EXPLANATION OF THE PLATES. 



Plate 53. 



Fig. 1. Cryptophallus bartschi, new species, about natural size. 



2. Thysanosoon auropunctatum Kelaart-Collingwood, about X2. 



3. Pseudoceros hancockanus (Collingwood), about X2. 



4. Pseudoceros litoralis Bock, about X2. 



5. Pseudoceros buskii (Collingwood), about natural size. 



6. Pseudoceros concinnus (Collingwood), about natural size. 



Plate 54. 



Fig. 7. Pseudoceros rubrotentaculatus, new species, X5. 



8. Pseudoceros philippinensis, new species, X2. 



9. Prostheceraeus papillo (Kelaart), X2. 



10. Prostheceraeus melcagrinus (Kelaart), X5. 

 11.- Simpliciplana marginate, new species, X2 



8 Von Plehn, 1806, Jena. Zeitschr., vol. 30, p. 167, pi. 13, fig. 12. 



o 



