JOHN B. SMITH, SC.D. 355 



the U. S. National IMuseum the primaries are iu most cases quite 

 uniform, but rather unusually intense brown, and the secondaries are 

 blackish ; but the palest specimen is paler throughout, and the only 

 mottled example has the secondaries also mottled. I have attempted 

 to determine whether locality had anything to do with the amount 

 of mottling; but this seems not to be the case. Series caught at 

 one time in one place are apt to be very similar; this is proved by 

 the series from Manitoba, and by the material from Cohasset; but 

 in the U. S. National Museum collection there are 28 examples from 

 one general region in New York State, and the full range of 

 variation is represented in this lot. Thirteen of these examples 

 are from Mr. David Bruce, and while most of them are dark or 

 strongly mottled forms, the more uniform red-brown forms are also 

 represented. 



Altogether this is an excellent example of a decidedly variable 

 species, with two well-marked forms connected by a full series of 

 intergrades. Typical hicolorago is rare; forms nearly immaculate 

 are also rare ; the mottled form in which there is a more or less 

 diffuse median shade and a dusky subterminal space is by all odds 

 the most common. 



The large series of dry specimens from Cohasset, to which refer- 

 ence has been made, gave an excellent opportunity for studying the 

 structure of the hair pencil which is attached to the base of the 

 abdomen in the male. The first abdominal segment is dorsal onlv, 

 and ends at the lateral line of the body where the front margin of 

 the ventral portion of the second abdominal segment joins the tho- 

 racic structure. Attached just at the extreme outer edge of this 

 second segment, where it joins the dorsal portion of the first seg- 

 ment is a long strip of chitin, broadening toward the lateral margin 

 and from there produced into a long curved stalk, at the end of 

 which is a round concavo convex disc-like structure. The curva- 

 ture of this stalk is such that when at rest it lies close along the 

 edge of the first segment. The under or concave side of this disc is 

 set with pittings, and from the margins of these pittings comes a 

 dense mass of very long fine hair, forming a slender pencil, almost 

 half the length of the abdomen. This pencil normally fits into a 

 membraneous pocket which is attached on the inner wall of the 

 abdomen, reaching to the end of the fourth segment. The opening 

 to this pocket is on the lateral line of the second and third segments, 



TEANS. AM. KNT. SOC. XXXIII. DRCEMBEE, 1907. 



