I 



THE CANADIAN ENTOMOLOGIST. 103 



ON THE POSITION OF THE GENUS DEMAS. 



BY HARRISON G. DYAR, PH. D., NEW YORK. 



In the March number of the Can. Ent., pp. 81-82, Mr. Tutt falls 

 back upon the writings of Dr. Chapman to support his position for this 

 genus 3,s among the Liparidfe*. As Mr. Tutt has thus gracefully retired 

 from the discussion without making a direct answer to my facts, I can 

 only, in reply, briefly notice Dr. Chapman's position. 



In the egg of Demas, Dr. Chapman, on a matter of detail, seems to 

 imply an absence of relation with the iVpatelidse ; but the fact remains 

 that the egg is vertically ribbed as in the Noctuidfe, Apatelidae, and 

 Thyatiridge, which I take to be the essential character. The Lymantriidse, 

 which belong to the Notodontian-Lasiocampid series have smooth, or 

 obscurely reticulated eggs, the vertical lines having no tendency to 

 become prominent. 



In the young larva. Dr. Chapman has not discovered the peculiar 

 arrangement of the warts, on which I lay special stress. He would ally 

 Demas to Liparis on " the abundance of hairs and their length, the 

 character of the tubercles, the anterior trapezoidal being more important 

 than the posterior and the colouring." The hairs and colouring may be 

 dismissed at once, as they are notoriously adaptive and variable charac- 

 ters. The statement about the tubercles is surprising. While it is 

 correct of Demas as figured, the reverse is strikingly the case in many 

 Lymantriids. The anterior trapezoidal (tubercle i.) in this group have 

 a marked tendency to disappear, and I can only suppose that Dr. Chap- 

 man has made some mistake. His own figure of Dasychit-a pudibunda 

 (pi. ix., fig. 8) shows the anterior trapezoidals clearly the smaller. The 

 structure in Demas really tells in favour of my view. 



In the second skin, Dr. Chapman describes a medio-dorsal depres- 

 sion on joints 5 to 1 1 and 12 "in the position of a peculiar organ in 

 various Liparids." I see no good reason for the inference that these are 

 the homologues of the dorsal eversible glands of the Lymantriidie. In 

 the first place they seem not to have any indication of the structure of 

 such glands, and in the second place they are not homologous in position. 

 In the Lymantriidse, the glands occur on the loth and nth segments 

 only ; when others appear on the anterior abdominal segments, as in 

 StilpHotia sa/icis and Lymantria dispar, they are paired, not single. 



*The name Lymantriidre, as this family "appears to be called by American 

 authors," was adopted by me from Mr, G, F. Hampson's Moihs of India. 



