401 



Chilton, from Coogee Bay, New South Wales; D. aucklandiae, 

 G. M. Thomson, from Lord Auckland Islands, New Zealand; 

 and D. bucculenta, Nicolet, from New Zealand and from 

 Valparaiso Bay, South America. The species are all found 

 on the sea shore at or near high-water mark, and show strik- 

 ing secondary sexual characters which differ considerably in 

 the different species. 



At the time of writing the paper I had only the few 

 original specimens of D. marina, of which only one female 

 was mature, and the description of this species was therefore 

 somewhat imperfect. I added to it the remark (1915, p. 445), 

 "The adult male is not known ; it will be interesting to see 

 in what characters it differs from the female." Some months 

 after the MS. had been despatched to the printer, I received 

 from Mr. W. H. Baker, of Adelaide, a few specimens of an 

 Isopod that he had collected on the shore of Kangaroo Island, 

 South Australia. On examination these proved to belong to 

 Deto marina, and among them were adult males and females. 

 I am therefore able now to complete my description by adding 

 that of the adult male and to point out the sexual characters. 

 In this case the male characters prove to be a greater elonga- 

 tion of the uropoda, and a more distinctly tuberculated char- 

 acter of the dorsal surface of the body. The antennae, which 

 show such marked sexual dimorphism in D. aucklandiae, are 

 practically the same in both sexes in D. marina, and there is 

 no sign of the dilatation of the first peraeon segment in the 

 male such as occurs in D. bucculenta. At the same time I 

 give a description and figures of the first and second pleopoda 

 of the male and female, from which it will be seen that they 

 are in close general agreement with those of the other species. 



The specific description I gave in 1915 applies with very 

 slight modification to the females from Kangaroo Island. In 

 the following account I have drawn up a corresponding 

 description of the male. 



Deto marina, Chilton. 

 Figs. 15-21. 



Philougria marina, Chilton: 1884, p. 463, pi. xi. ; Stubbing: 

 1900, p. 565; Chilton: 1901, p. 128. 



Deto marina. Budde-Lund : 1906, p. 85, pi. iv., figs. 39-41; 

 Chilton: 1915, p/444, pi. xxxix., figs. 19-23. 



Specific Description. 

 S ■ Body oblong-oval, length rather more than twice the 

 greatest breadth. Head with surface covered with irregular 

 rather spinose tubercles, front projecting into a triangular 

 lobe ending subacutely, lateral lobes very broad. Eyes large, 

 on rounded prominences raised above the lateral lobes. 



