Februaby 23, 1906.] 



SCIENCE. 



313 



graph, with a view to the bringing about of 

 a more natural grouping of these forms, for 

 use in a circular soon to be issued by Dr. L. 

 0. Ploward; as the character of that publica- 

 tion precludes the giving of an exposition of 

 the subject, it has been thought best to give 

 this in the pages of Science. 



I first made a critical study of the members 

 of this genus in the year 1895,' and was im- 

 pressed with the importance of the structure 

 of the tarsal claws of the female — whether 

 toothed, or simple — and later began all of my 

 published synoptic tables of the species with 

 this character. The present study has but 

 confirmed the correctness of that first impres- 

 sion — that all of the species with simple claws 

 in the female are more nearly related to each 

 other than they are to any species in the series 

 having the claws toothed, and vice versa. 

 Several months ago Miss E. G. Mitchell ex- 

 pressed the opinion that those species which 

 lay their eggs in masses form a natural group 

 by themselves, and stated that their larvae 

 possess important structural characters not 

 found among those belonging to the single- 

 egg group. That the difference in the manner 

 of egg-laying is an important one admits of 

 no argument; even the enveloping membrane 

 is structurally different in the two kinds of 

 eggs. Applying the egg-laying habit, so far 

 as this is at present known, to the members of 

 the two tarsal-claw groups, it was ascertained 

 that all those with toothed claws deposit their 

 eggs singly, while those with simple claws lay 

 their eggs in masses with the exception of a 

 single genus (Orahhamia). This was suffi- 

 cient agreement to indicate an evident correla- 

 tion existing between the egg-laying habits 

 and the character of the tarsal claws. Next, 

 by taking jointly the more prominent char- 

 acters from both adults and larvae a rational 

 and natural grouping resulted, as may be seen 

 by reference to the accompanying table : 



A. Tarsal claws of the female simple, scales of 

 the mesonotum and the outstanding ones on the 

 wing veins narrow and almost linear. 

 B. Eggs laid in masses. Larva having more 

 than one pair of tufts or of single hairs on 

 ' See the Canadicm Entomologist for 1896, page 



43. 



the breathing tube, or else with ten or more 

 bristles in continuation of the two rows of 

 spines. Tarsi of the adult white at each end 

 of some of the joints', or else wholly black, 

 in which latter case the abdomen is black 

 scaled, sometimes with basal light colored 

 bands on the segments. 



C. Hind cross-vein of the wings more than its 

 owm length distant from the small, palpi 

 of the male exceeding the proboscis by more 

 than the length of the last joint, densely 

 long-haired. Larva with more than one 

 pair of tufts or of single hairs on the 

 breathing tube, the two rows of spines never 

 continued by bristles, antennal tuft situated 

 in a distinct notch (pipiens, etc.). 



Gulex Linng. 

 CC. Hind cross-vein less than its length from 

 the small, palpi of the male scarcely ex- 

 ceeding the proboscis', sparsely short-haired. 

 Larva with only one pair of tufts on the 

 breathing tube, situated close to its base, 

 the two rows of spines continued by ten or 

 more bristles, autennal tuft never in a 

 notch. 



D. Scales of the wings uniformly dis- 

 tributed (absohrinus, etc.). 



Culiseta Felt. 

 DD. Scales much more dense on some por- 

 tions of the veins than on other portions 

 ( annulatus, etc. ) . 



Theobaldia Nev. Lem. 

 BB. Eggs laid singly. Larva having only one 

 pair of tufts on the breathing tube, the two 

 rows of spines composed of from four to six 

 spines each, the rows never continued by bris- 

 tles', spines on either side of the eighth seg- 

 ment of the abdomen very large, from four 

 to six in number, arranged in a single row. 

 Tarsi of the adult white at the bases' only of 

 some of the joints, or else wholly black, in 

 which case the abdomen is black scaled and 

 with the front corners of the segments white 

 scaled (jatnaicensis, etc.). 



Grabhamia Theob. 

 AA. Tarsal claws of the female toothed in at 

 least the front and middle feet. Eggs laid 

 singly. Larva with only one pair of tufts on 

 the breathing tube (except in cinereoborealis) , 

 the two rows of spines composed of ten or more 

 rather small ones in each row, the latter not 

 continued by bristles. 



E. Scales of the mesonotum narrow, almost 

 linear. 

 F. Outstanding scales of the wing-veins nar- 



