88 DR. COLLINGWOOD ON THIRTY-ONE 



Family TYPHLOLEPTID^]. 

 Genus Typhlolepta, Oerst. 



22. Typhlolepta Byerleyana, Coll. Pulo Barundum, west coast of Borneo. 



Family LEPTOPLANID^]. 



Genus Centrostomum, Diesing. 



23. Centrostomum ocellatum, Kel. Ceylon. 



24. Centrostomum punctatum, Kel. Ceylon. 



Genus Elasmodes, Le Conte. 



25. Elasmodes obtusus, Coll. Singapore. 



Genus Leptoplana, Hemp, et Ehr. 



26. Leptoplana patellensis, Coll. Simon's Bay. 



27. Leptoplana aurantiaca, Coll. Singapore. 



Family STYLOCHID^]. 

 Genus Stylochoplana, Stimpson. 



28. Stylochoplana elegans, Kel. Ceylon. 



29. Stylochoplana meleagrina, Kel. Ceylon. 



Genus Stylochopsis, Stimpson. 



30. Stylochopsis malayensis, Coll. Pulo Barundum, west coast of Borneo. 



Family PLANOCEKID^. 

 Genus Planoceea, Blainv. 



31. Planocera thesea, Kel. Ceylon. 



IV. 



(Descriptions of the Marine Planarians collected in the Eastern Seas by Dr. Colling- 

 wood, F.L.S., and delineated in the accompanying figures.) 



1. Thysanozoon Alderi. 

 Length 2\ inches ; breadth 1^ inch. 

 Body thin, with very irregular margin, amply folded and puckered. 

 Upper surface of a general light brownish colour, with a narrow, pale external margin, 

 within which is a broad, black border, somewhat shaded and marbled. Down the 

 median line for about three quarters of its extent runs an irregular, black marbling ; 

 a faint marbled pattern of pale brown is diffused over the general surface ; and a 

 lens discloses also a fine ramification of a darker tinge throughout. 



The whole upper surface is studded with small papillae of a conical form, the foot- 

 stalks of which are pale, and the distal extremities orange. Many of these papillae 



