1878.] 435 [Uhler. 



the female broadly black on the middle. The cerci of the male are 

 long, slender, curved, hairy processes. Length, 3^-4 millims. 

 Breadth of pronotum, If millims. 



I am deeply indebted to my much lamented late friend, Dr. James 

 B. Bean, of Baltimore, for ample series of this species from the moun- 

 tain and valley streams of eastern Tennessee and western North and 

 South Carolina. The specimens from the valleys are mostly winged, 

 while none of those from the great altitudes are so. For a period of 

 fifteen years I have observed these insects in Maryland, eastern Vir- 

 ginia and Pennsylvania, and have also seen many specimens from 

 Massachusetts and Canada, but from these localities always with- 

 out wings. The cognate species, R. collaris Mayr, is very com- 

 mon on the surface of the Grand Anse River in Haiti ; where I ob- 

 served and collected both winged and unwinged individuals from a 

 single colony. Having the true R. collaris Burm. in my collection, I 

 am thereby enabled to mark the differences between it and our new 

 species. The R. collaris Burm. is also a native of Cuba, from which 

 locality I have examined specimens. 



hygrometrid^s. 



Hygrotrechus Stal. 



1. H. remigis. 



Gerris remigis Say, Hemipt. New Harm., 35, 1. 



No. 15? (sic) Harris' Collection, cf. No. 14, ?. " Charles River." 

 " Larva, July 20, 1827." 



One individual of each sex, labelled "Maine." I have examined 

 specimens of this species from many parts of the United States and 

 Canada. It is quite common, and sometimes abounds in Maryland ; 

 but near Baltimore it is never winged. Individuals differ in color, 

 many being reddish brown, or ferruginous on the base of the prono- 

 tum, but the most usual color is fusco-olivaceous. The emargination 

 of the last ventral segment (cf), together with the shorter, robust cerci 

 will distinguish this species from its nearest allies. The cerci in the 

 present specimens are a little shorter than usual. Determined as G. 

 remigis by Mr. Say. Another specimen, with printed number 144, is 

 in the collection. 



2. H. conformis, n. sp. 



"Velia collaris Say, MSS., named by himself. On water, Septem- 

 ber 30." 



