SPECIES OF MARINE PLANARIANS. 89 



arise from an elevated white spot or tubercle, such tubercles producing only one 



papilla each; and other papillae exist upon the black margin, as well as on the 



general surface. 

 Under surface whitish, edged with black, the part answering to the black marbled line 



on the dorsum being here opaque white. 

 Head blackish, angular, raised somewhat above the general plane of the body, flexible, 



and having two projecting angles or folded tentacles. 

 This was a very beautiful and striking animal, looking as if studded with golden beads. 

 It swam freely, with a graceful vertical vermicular movement of the ample sides. 



One was found under stones about two feet under water at low tide, upon a reef of 

 the island of Labuan, coast of Borneo, on August 22. I have great gratification in 

 naming it after the late Mr. Joshua Alder, of Newcastle, a gentleman with whom I was 

 long in correspondence, and from whom, though we never met, I always received 

 uniform kindness and urbanity. 



Fig. 1 : a, general appearance of upper surface ; b, head and tentacles ; c, portion of upper surface, 

 enlarged, showing papillae ; d, a papilla ; e, a papilla-bearing tubercle. 



2. Thysanozoon Allmani, Coll. 

 Length 2^q inches ; breadth f inch. 

 Body translucent, papillose. 



Upper surface light brown, becoming darker towards the margin, and with an irregular 

 edging of opaque white all round, excepting the head. An elevated ridge runs 

 along the median line of the dorsum. 



The whole upper surface is covered with clavate and pointed papillae, of a deep 

 brown colour, and varying in size, the smallest being the lightest-coloured and most 

 numerously clustered, and occurring along the median ridge. 

 Under surface grey, darkening to deep brown at the sides, and edged with opaque 



white. 

 Head with two long tentacles, often thrown back, and presenting the appearance of 

 hare's ears. Tentacles dark brown, tipped with white. Two minute white tentacles 

 are situated in front of the head, beneath the hare-like ones. 

 Eye-spots situated in a light-coloured spot immediately posterior to the head, in a double 

 cluster, consisting of two small crescentic patches of minute black spots. 

 A splendid species, the edges much corrugated, unless the animal is in full movement, 

 when the folds almost disappear. It swims freely, with a graceful serpentine movement, 

 and crawls with moderate rapidity and with an undulating movement. "When at rest 

 the animal assumes a nearly circular form, with numerous marginal folds. 



Two specimens found at Singapore, west of the harbour, under pieces of dead coral, 

 on the beach between tide-marks, Nov. 22nd. 



I have much pleasure in connecting this species with the name of the President of this 

 Society, so well known for his researches among the Invertebrate division of animals. 

 Fig. 2 : a, animal in movement (dorsal surface) ; b, papilla?, large and small, magnified ; c, eye-spots 

 (magnified). 



