BY R. J. TILLYARt). 3§ 



Methods of Study. 

 A. The living larva. 



For studying the living larvai, I used two large aquaria, and 

 eight smaller observation jars. All these were provided with a 

 bottom of clean sand, in which VaUisneria and other water- 

 weeds were grown. For the rock-dwelling larvji^, I used two 

 puppy's drinking-tins, about three inches deep and one foot in 

 diameter. In these was placed a layer of fine sand, with a 

 number of small rocks, leaning against one another at various 

 angles. A depth of only about two inches of water is required 

 in these pans. As no water-weed is grown in them, the water 

 was allowed to evaporate, and fresh water added every two or 

 three days. 



The larvtt of Dlphlehia,, Neosticta, and Arg'wlfMes, being rock- 

 dwellers, were left in the tin pans. All the rest were kept in 

 the large aquaria, except when a particular species was under 

 observation; in which case it was removed to one of the observa- 

 tion jars for closer study. The aquaria, jars, and pans were 

 covered with cages of jnos<iuito-netting on wire frameworks. By 

 this means T was enabled to breed out the imagines of every 

 Australian species made use of in this paper, and so to deter- 

 mine every larval form with certainty.* Full descriptions of 

 these larva? will be given in a future paper. 



In studying the gill-system, it is necessaiy to use the living 

 larva in order to determine the following points: — 



(i.) The natural position of the three gills, i.e., whether pressed 

 against one another or lield wide apart, and, if the latter, the 

 approximate angles between them; also, whether each separate 

 gill is held in a vertical or horizontal plane, and whether, in the 

 case of the lateral gills, the mid-rib, or thickened edge of the gill, 

 is placed externally en- internally, dorsally or ventrally. 



(ii.) Whether the gills are an aid or a hindrance during loco- 

 motion. 



'■' The laivff of Ceria(jriona,nd Aiistrocntmis ^\■ev^i bred out in the Queens- 

 land Museum, where the Director, Dr. R. Hamlyn-Harris, very kindly 

 lent me a room and aquaria durin<^ SeptemV>er, 1915. 



