334 



JOHN B. SMITH. 



Fig. 15. Pseudo 

 trachea (?) of Doli- 

 chopodid. 



CecL 



iSome specimens of a Dolichopodid, prepared for examination, 

 proved failures, owing to a lack of differentiation in the mounted 

 material, and only a very unique character on the 

 galear envelope was noted. 



Instead of the pseudo-trachea, or the wrinkled 

 structure often representing it, we iifid here a series 

 of geminate tubercles, decreasing in size from the 

 maro-in, and ending in the membrane. I have not 

 seen this appearance in any other species, and could 

 not study more than the one species of the family from lack of material. 

 As suggested above, in all of the forms last treated, the jjroboscis 

 is not hinged or folded, 

 and in none do we find 

 any trace of a basal pro- 

 longation of the palpifer; 

 that organ itself becom- 

 ing very much reduced. 

 In all the following spe- 

 cies the proboscis is 

 hinged and the galea 

 development is of the 

 same type. This type is 

 best illustrated by a 

 diagrannriatic view of the structure in Eris- 

 talls trcmsversus, in which the chitinous 

 renmants of the galea are so arranged that 

 their character is obvious. The subgalea 

 is united, but the suture is evident, and 

 the lobes, almost entirely separated, easily 

 show their jointed nature. With this 

 diagram for reference, the figure of Eris- 

 tdiis fenax may be presented. In it will 

 be necessary to premise, that the mem- 

 brane enveloping the mouth is extremely 

 extensile, and that, in nature, the tip of 

 the labium extends to the tip of the sub- 

 galea or very near to it. This latter 

 part is a single plate, but the suture is 

 evident, and it is plainly composed of two 

 similar pieces. The labium is completely 

 Fig. 18. Mouthof ^r«/«/«^^«a^.gj^yg]^pg^ ^y ^^^ kciuia, which do not, 



however, extend to the base. The ligula is well distinguished, and. 



Fig. 17. Erisialis 

 transversus. 



