Dr. A. Giinther on Hydromedusa. 421 



(c) A rather distinct-looking species allied to A. hepatica, 

 ]\]cLaclil., and resembling it in colour, thongh with the neura- 

 tion of the wings quite obscure. Tt has three series of 

 gradate nervules on the anterior wings. I do not venture to 

 name it, having only a female specimen, which I captured on 

 Haleakala, Maui. 



Myrmeleontidae. 

 It seems a singular thing that I have met with the one 

 species of this family known as Hawaiian only in a single 

 ravine on Maui, though there it is common enough, and so 

 conspicuous as to seem incapable of escaping notice. It is 

 fairly strong on the wing. 



In conclusion I will just say that the non-existence or (more 

 probably) rarity of the Trichoptera is in accord with the state 

 of affairs in other orders. All water-frequenting insects are 

 scarce, the described Dytiscidoe being represented by three 

 (one of which is unique), the Ilydrophilidaj by one, and the 

 true water-bugs by two species respectively. There scarcely 

 can be said to be any constant fresh water on the islands. I 

 am not aware of any permanent natural freshwater lake ; at 

 any rate, the only one I know that is probably permanent is 

 at an elevation of near 15,000 feet above the sea. (When I 

 visited it, it was frozen over.) There are springs here and 

 there, one of which was a favourite hunting-ground with me, 

 as its moisture attracted insects to the neighbourhood ; but I 

 feel sure that no Trichoptera occur there. There are also 

 streams which do not absolutely disappear in dry seasons ; 

 but the natural state of the islands, apart from modern ar- 

 rangements for the artificial preservation of water, is that of 

 possessing very little permanent water really fresh. On one 

 of the islands (Lanai) it is said that the horses and other 

 animals do not know how to drink. Thecomparative abundance 

 of Agrionidge is remarkable, and I know not how to account 

 for it. 



Port Lincoln, Soutli Australia, Oct. 1884. 



LIII. — Contrihution to our Knowledge of Hydromedusa, a 

 Genus of South-American Freshwater Turtles. By Dr. 

 A. GiJNTHEE, F.R.S. 



[Plate XIV.l 



Haying recently received a very well-preserved and inter- 

 esting specimen of Hydromedusa from fresh waters south of 

 Ann. & Mag. N. Hist. Ser. 5. Vol. xiv. 32 



