ZooL.— Vol. III.] SNODGRASS—DOLICHOPODID HYPOPYGIUM. 283 



Liancalus hydrophilus Aldrich. 



Plate XXXIII, Figs. 3 and 8. 



This species has a long slender cylindrical abdomen, the 

 pregenital part formed of the first six segments. The sixth 

 segment (fig. 3) is unusually large, having a well developed 

 tergum and sternum. The seventh segment (fig. 8, vii, 

 t. and s.) is almost rudimentary, consisting of a narrow 

 chitinous ring formed of the tergum (/.) and sternum (s.), 

 entirely concealed within the sixth segment. The eighth 

 segment is relatively large, and is triangular in lateral view 

 (fig. 8, viii). The upper margin is curved, but the lower 

 is prolonged downward to a sharp point. It covers nearly 

 the entire left side of the ninth. The latter (fig. 8, x) is 

 small, and is irregularly quadrate in lateral view. The lower 

 angles are prolonged into small triangular lobes (<i). 

 There are two lateral pairs of posterior clasping append- 

 ages i^a and <5) present. The penis and its sheath are 

 entirely inclosed within the genital chamber. 



The paranal lobes of the tenth segment are remarkable 

 for their length (fig. 3). They form a pair of long taper- 

 ing appendages sparsely covered with very long hairs, and 

 when turned forward reach to the thorax. Ordinarily the 

 hypopygium is almost entirely concealed within the sixth 

 segment (fig. 3), so that the long anal lobes appear to arise 

 from the end of the pregenital part of the abdomen. 



Porphyrops longipes Loew. 

 Plate XXX, Fig. 10. 



This species is very similar to Liancalus hydrofhilus^ 

 especially in having the anal lobes long and tapering. The 

 species is, however, in general, intermediate between 

 L. hydrofhilus and those species presenting the more 

 ordinary structure. The anal lobes are not nearly so long 

 as in Liancalus hydrophilus, and both the eighth and the 

 ninth segments of the abdomen are exposed. 



