370 Mr. C. Chilton on Polymorphism 



remarked upon the resemblance of Microdeuteropus maculatus 

 to Aora typica in the following words : — " Though dissimilar 

 in many respects from Aora typica, there is such a strong 

 resemblance in other points that I should not be surprised if 

 they prove to be male and female of the same species, in 

 which case the generic character of Aora will require modifi- 

 cation. Can it be a case of protective resemblance?" *. 



In 1881 I took numerous specimens of Microdeuteropus 

 maculatus in Lyttelton Harbour, and with them a form closely 

 •resembling them in all respects except in the first gnatho- 

 poda, which were "complexly chelate," like those of Aora 

 typica, though differing in some minute details ; and in a 

 paper published in the ' Transactions of the New-Zealand 

 Institute,' vol. xiv. p. 173, I suggested that most probably 

 this form rather than Aora typica was the male of Microdeu- 

 teropus maculatus. (In referring to this form I shall speak of 

 it as " Microdeuteropus maculatus ^ , Chilton.") Afterwards 

 I took Aora typica also in Lyttelton Harbour, and was thus 

 able to see that, though it was really somewhat different from 

 Microdeuteropus maculatus (^ , Chiiton, as I had previously 

 stated, it was, like that form, essentially similar to Micro- 

 deuteropus maculatus $ , Thomson, except in the first gnatho- 

 poda. About the same time I heard by letter from Mr. 

 Thomson that he had taken a large number of specimens of 

 Aora typica and Microdeuteropus maculatus $ , both at the 

 same locality, and felt convinced that they both belonged to 

 one species. While in Sydney, in January 1884, I obtained 

 specimens of Microdeuteropus Mortoni, Haswell, and also of 

 M. tenuipes, Haswell. One of my specimens of the latter 

 species was a female bearing eggs, and from the close resem- 

 blance of the two I suggested f that M. Mortoni was probably 

 the male of M. tenuipes. I also remarked upon tlie very close 

 resemblance between M. tenuipes and M. ?naculatus $ , and 

 between M. Mortoni, M. maculatus ^ , Chilton, and Aora 

 typica, in all points except in the first gnathopoda ; but at 

 the time I left the species as distinct, until further evidence 

 should be forthcoming. Since then 1 have examined the 

 various forms more minutely, and have compared them with 

 Dunediu and Stewart-Island specimens of M. maculatus $ 

 and Aora typica, which were very kindly placed at my dis- 

 posal by Mr. Thomson, and I now feel convinced that they all 

 belong to one species, of which we therefore now know three 

 forms of the male and one of the female. 



The different forms vary somewhat in several small points ; 



* ' Transactions New-Zealand Institute,' xiii. p. 218. 



t ' Proceedings Linneau Society N. S. W.' vol. ix, part 4, p. 1040. 



