XXII. FREvSH WATER PLANARIA. 



By Richard H. Whitkhouse, M.Sc, Zoological Department, 

 Queen's University, Belfast. 



(Plate xxii.) 



The collection of freshwater Planarians made in the Abor 

 country consists of two species onl}^ both found under stones in a 

 hill-stream. I am asked to state that some of the specimens were 

 collected and preserved by Capt. F. H. Stewart, I. M.S. 



Planaria aborensis, n. sp. 

 (Plate xxii, figs. 1-3.) 



This species bears a striking resemblance to Planaria snhtenta- 

 culata (Draparnaud in such features as the shape of the head, the 

 absence of male genital organs and the much branched alimentary 

 canal. The collection also included a number of young specimens 

 which were produced by transverse fission, and which corresponded 

 exactly with the form of newly budded animals of P. suhtentaculata 

 as figured by Zacharias (4). 



However, the very definite colouration the animals possess, 

 and which is quite different from P. suhtentaculata, as well as some 

 internal anatomy, at least not recorded for this species, seemed to 

 me to justify its separation from P. suhtentaculata, and I have 

 therefore called it Planaria ahorensis. 



All the specimens were collected in the Yembung stream at an 

 altitude of iioo ft , and were found on the under surface of 

 stones. 



The collection included 22 animals of this species; most of 

 the specimens were much contorted, but a few remained extended. 

 Of these the large ones measured 9 mm. in length and 2 mm. 

 across the widest part of the trunk. The head (fig. i) is triangular 

 in form, often markedly so, with a prominent lappet on each side, 

 which gives the animal a distinct neck. The posterior end of the 

 body tapers bluntly. In colour, the dorsal side of the body is a 

 rather light brown with a definite line of much darker tone running 

 in the middle line along the length of the body from the neck to 

 the posterior; this darker line expands at about the midUe of its 

 course, at the root of the pharynx, into a broad patch. 



The crescentic e^^es, which are two in number, are situated 

 about midway between the anterior extremity and a line drawn 

 across the head from the extreme points of the lappets at the side ; 



