186 MESOZOIC INSECTS OF QUEENSLAND,!, 



the H ydropsychinm as being the closest existing relatives of the 

 Mesopnychidie, both in the general shape of the forewing, the 

 relationships of the main veins and branches inter se, and, in 

 particular, the structure of the discoidal and median cells {cf. 

 Text-figs. 2, 3, 4). 



If we compare the forewings of Mesojy^yche and Trinssojysyche 

 with that of llydro-psyche (Text-fig. 4), we shall notice the follow- 

 ing resemblances and differences : — 



(1) The general shape of Hydropityche closely resembles that 

 of Triassopsyche. Mesopsyche has a wing distinctly narrower 

 than that of most Hydropsy chince . 



(2) Hydropsyche has lost all but the most basal of the costal 

 cross-veins. There are, however, a number of recent genera of 

 Hydropsychhuf possessing one or more extra costal cross-veins, 

 e g., ChJorop)syc.h6^ ^thalojUera, Amphipfiyche, Phcniostoma, and 

 Polymoiyhaniaihs. We may see in this a persistent archaic char- 

 acter handed down from ancestors closely resembling our two 

 Ipswich genera. 



(3) In Hydropsyche, the ptei-ostigmatic area has become re- 

 duced and left incomplete proximally, by loss of the cross-vein 

 below Sc. There are other genera of Hydropsy china', however, 

 in which the cross-vein still persists (e.g., Smicridea). 



(4) In Hydropsyche, Af.l is no longer sessile upon dc, but has 

 become distinctly stalked. Similarly, Af.3 is stalked from mc. 

 Af.2 and Af.4 remain sessile upon dc and mc respectiveh', but 

 not so completely as in the Mesopsychidce. The character of 

 possessing all four forks (Af. 1-Af 4) sessile upon their respective 

 cells is retained in a few recent genera, e.g., Anisocentropus in 

 the ('alamoceratidie. In this latter genus, the structure of dc 

 and mc and the forks arising from them very closely resembles 

 that seen in 7\ias8opsyche. The importance of this character, 

 from a phylogenetic standpoint, may perhaps be emphasised by 

 a phylogenetic diagram (Text-fig. 5), in which all stages are 

 shown, from the original archaic formation (A) down to the 

 most advanced ceenogenetic form (D), in which the two forks 

 are stalked. In this diagram, the cell may be taken either as dc 

 or mc: if the former, the upper fork is Af.l, the lower Af.2; if 



