500 STUDIES ON AUSTRALIAN MOLLUSCA, 



broad. The interior not visible from above through the oblique 

 passage, divided into two chambers by the septum. Septum 

 advanced to a third of the shell's length into the cavity, project- 

 ing a median sinus, recurved upwards and forwards on each side 

 to join the shell wall. Margin expanded, externally marked off 

 by a furrow. Length 2*32, breadth 1*48, height 1-28 mm. 



Hab. — La Perouse, N.S. Wales (H. L. Kesteven); one speci- 

 men, in shell sand. 



Typ,e to be presented to the Australian Museum. 



This species is named in honour of one of my most successful 

 pupils, Mr. H. L. Kesteven, a gentleman to whose talents both 

 as a student and a collector I have been frequently indebted for 

 assistance. Only two species of this genus have hitherto been 

 recorded from Australian seas. From P. harrisoni, Beddome, 

 ( — P. henniana, Brazier)* and from all named species the hump- 

 backed shape and great development of the septum amply dis- 

 tinguish the novelty. But it is probably allied to, and possibly 

 identical with, an unnamed species noted by Watsonf from 

 Torres Straits. 



Crosseia labiata, Tenison-Woods. 



Ten. -Woods, Proc. Roy. Soc. Tasm. 1875, p. 151. 



(Plate xxvi., fig. 18.) 



This species was first recorded from this coast by Mr. A. U. 

 Henn. % As it has never been illustrated, I now give a figure of 

 an authentic Tasmanian example kindly furnished by the Rev. 

 H. D. Atkinson. The individual figured is 3 mm. in length. 



Nerita melanotragus, Smith. 



The proper name of our common black Nerite has been a 

 difficult matter to settle. Dr. Boog Watson in the "Gasteropoda 



* Proc. Linn. Soc. N.S. Wales, (2) ix. 1894, pi. xiv., figs. 14a, Ub. 

 t Chall. Report, Gasteropoda, p. 42. 

 I Proc. Linn. Soc. N.S.W. xxi. 1896, p. 500. 



