494 



NEW YORK STATE MUSEUM 



at apex, strongly expanded at the base and extending beyond the 

 lobes. 



Megarhinus portoricensis Von Roder. Genitalia, male. Basal 

 clasp segment stout, subtriangular, tapering to a narrowly rounded 

 apex. Terminal segment rather slender, base slightly enlarged, tip 

 slender, bearing a rather long, acute terminal spine. Claspette 

 represented by a simple, broadly rounded basal setaceous lobe. 

 Harpes long, excavated externally and terminated by a stout, 

 chitinous spine and a series of minute denticulations. Harpa- 

 gones slender, closely appressed, ventral edge with a series of 

 minute teeth. Unci fused, slender, ending in acute points. Set- 

 aceous lobes moderately well developed, thin, bearing numerous 

 long, rather slender setaceous spines. Seventh segment with a 

 transverse row of very long slender spines across the posterior third, 

 evidently a generalized type of the submedian groups of spines 

 observed in some other genera. [PI. 19, fig. i] 



The Corethrinae are a fairly homogeneous subfamily, despite the 

 wide differences in larval structures, though there is a substantial 

 agreement in habits, all being aquatic and predaceous. Core- 



thrella appears to be the 

 more generalized of the 

 various genera, there be- 

 ing comparatively slight 

 differences between the 

 antennae in the two sexes 

 [fig. 2]. Those of the female 

 are remarkable because of 

 the rudimentary whorl of 

 hairs near the middle of 

 each segment, and those of 

 the male are unique on ac- 

 count of the long, fine hairs 

 continued to the apical 

 fourth. The wings of both 

 sexes are substantially alike , 

 both possessing the obli- 

 que scales along the mar- 

 gin, a character almost uni- 

 versally limited to the 

 female. The claws are sim- 

 ple in both sexes, though 



FiG.Tio Corethrellabrakeleyi. dorsal view -^hose of the forC and mid- 

 of larva showing the peculiar head struc- 

 tures and the paired separate spiracles of \ o cr c nf fViP mnlp a r (^ 

 the air tube, much enlarged (Original) ^^gS OI tnC maie are 



