724 AUSTRALIAN HIRUDINEA, IV., 



bearing the large tubercular areas, and having double the width 

 of that anterior and posterior to it. 



PONTOBDELLA AUSTRALIENSIS, n.Sp. (Plate Ivii.) 



For the privilege of examining this leech, I am indebted, 

 through Professor Haswell, to Dr. Tidswell. In the collection 

 were about thirteen individuals of the same species, in various 

 conditions of retraction and extension. An examination of these 

 shows how easily mistakes have been made in the creation of 

 new species of this genus, inasmuch as the shape of the body and 

 general habit, and the importance of the papillae are so different in 

 contracted specimens. In such the otherwise prominent papillae 

 are hardly noticeable. 



In general appearance the species approaches closely to the 

 common European species, Pontohdella inuricata. 



Body. — The shape in various conditions of retraction is shown 

 in Plate Ivii. 



In an individual with well extended neck the measurements 

 were : — Total length, 20 mm.; neck, 8 mm.(exceedingly slender); 

 breadth of body, 3 mm.; depth of body, 3 mm. 



The neck is very strongly attenuated in a state of extension, 

 having a diameter of only 0*5 mm. 



Colouration. — In the preserved condition the neck-region is a 

 light yellowish-brown, and the body-region has a blue or bluish- 

 grey colouration. The posterior sucker and the region of a fe.w 

 annuli just anterior to it, have the same light appearance as the 

 neck. No trace of pigmented ornamentation is to be noted in 

 connection with the anterior sucker. 



Oral sucker. — Diameter 1 mm. On its margin are borne, on 

 either side of the mid-line, four, sometimes five, pairs of papilla?, 

 the fourth and fifth pairs, that is the posterior two, being usually 

 less strongly developed than the anterior two; and of' these, the 

 fourth is larger than the fifth. 



Oq the dorsal surface of the " head," a faint annulation can 

 be made out. 



Posterior sucker. — Diameter 1-5 mm. Traces of annuli can be 

 seen on the dorsal surface of this sucker. 



