LEPTIDJE. 41 



tains a number of species of wide distribution, specimens of 

 which are frequently found about the windows of dwelling 

 houses. The genus Olbiogaster has recently been described 

 from Mexico, " It differs from Rhyphus in the structure of the 

 head (eyes separated by a broad front in both sexes, and 

 occiput but very little developed), of the antennae (scapus 

 short, flagellum of male filiform, etc.), of the thorax and abdo- 

 men, as also in the venation." (Osten Sacken.) 



The larvae of Rhyphus are worm-like, legless, naked, more 

 or less transparent, with snake-like movements ; there are two 

 short fleshy points at the posterior end. The pupae are free, 

 inactive, with two projections anteriorly ; they live in water, 

 brooks, pools, or puddles, or in rotting wood, hollow trees, or 

 manure. 



13. LEPTID^. 



Species of moderate or large size, more or less elongated, 

 usually thinly pilose or nearly bare, without distinct bristles. 

 Males holoptic or dichoptic. Empodia developed pulvilliform, 

 the pulvilli present. Tegulae small or rudimentary. Third 

 joint of the antennae complex or simple, with or without a 

 terminal or dorsal arista or terminal style. Veins of the wings 

 distinct, not crowded anteriorily ; third longitudinal vein fur- 

 cate ; basal cells large ; five posterior cells usually present. 



As defined above, this family includes the Xylophagidae, 

 Leptidae and Coenomyidae of authors. It may be a question 

 whether this union is justifiable, but, on the whole, it seems 

 that the sole character which can be used to distinguish the 

 families the structure of the third aritennal joint divides 

 the group unnaturally, throwing with the Xylophagidse forms 

 whose affinities are greatest with the Leptidae, notwithstand- 

 ing the antennal character. 



The Xylophaginae include less than one hundred known 

 forms, and many of them are remarkable for their general 



