12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ill 



Brown. Other species of the aeripennis group were compared with 

 this description and differences noted and iUustrated. This procedure 

 was followed for each "species group," in each case the species 

 described in full being that for which there was the most suitable 

 material. 



In the study of the genera related to Ludius, only generic and 

 "species group" descriptions were prepared. Several specimens of 

 each of these species were examined carefully, but particular attention 

 was given to some 30 characters selected on the basis of the recon- 

 naissance survey and the detailed work with Ludius. 



Descriptions. — All descriptions were made from preserved speci- 

 mens, but living material was examined when available. The largest 

 and most perfect specimens were selected as the primary basis for 

 each description. All these (usually from three to six specimens where 

 available) were thoroughly examined. The remaining specimens were 

 used extensively in determining the individual variation, especially 

 in characters of setation and sculpture. After the morphological data 

 were analyzed the descriptions were revised to eliminate details com- 

 mon to all species. Each revised description was then checked by a 

 complete reexamination of a few larvae picked at random from the 

 available material. All specimens were examined in checking the 

 characters ultimately regarded as diagnostic. 



The head and mouthparts were examined under the compound 

 microscope using low and high power and occasionally oil immersion. 

 Most of the remaining parts were described from binocular examina- 

 tion, using a magnification of 64 diameters in studying the sculpture 

 and setae. Fine punctation is more readily observed on living speci- 

 mens ; consequently the preserved material was very carefully ex- 

 amined for the presence of minute pits. Such sculpturing, as well as 

 minute setae, was best observed by firmly gripping the larva with 

 tweezers and rotating it slowly while it was focused in strong light. 



The detailed descriptions are believed to be highly accurate, but 

 minute pores and minute setae are difficult to observe and subject to 

 considerable individual variation, the extent of which often was not 

 fully determined. These characters have been retained in the descrip- 

 tions for the sake of completeness, but rarely are they used as a basis 

 of identification. 



Illustrations. — Each figure is drawn from a single specimen and is 

 not a composite made up from observations on several individuals. 

 All drawings were made by the aid of an eyepiece micrometer and 

 cross-section paper. To facilitate comparison, a microprojector was 



