﻿NORTH AMERICAN NOTOSTRACA — LINDER 53 



In its general appearance, also, this species is suggestive of the genus 

 Le/pidurus. The body, because of its small number of rings, may be 

 almost completely covered by the carapace, which sometimes leaves 

 only part of the telson exposed. Such proportions are unusual in 

 the species of A'pus, and it is interesting to notice that they occur, 

 not in the species of Le/pidurus that have a similar number of rings 

 {L. bilobatus, L. lynchi), but in those that have the fewest rings. 



The number of abdominal leg-bearing rings, a figure that proved 

 helpful as a means of distinguishing groups within the genus Lepidurus 

 (p. 31), gives no clear character in Apus. In the whole genus, it 

 ranges from 12.5 to 20, figures that are generally higher than in Lepi- 

 durus. Im A. cancrijormis, the range is usually IG to 18, though I 

 have occasionally observed either fewer or more of such rings (the 

 fewest was noticed, not in this species, but in A. sudanicus, as noted 

 above, where a male has 12.5 and two females 13.5 and 14 such rings). 



The number of pairs of legs in various species is too little kno^v^l to 

 enable us to draw any conclusions about its taxonomic value. 



On the whole, we must admit that much work remains to be done 

 before we will be able to make a reasonably good arrangement of the 

 species of Apus. 



Distribution in America: Montana, Oregon, Wyoming, Calif oiiiia, 

 Nevada, Utah, Colorado, Nebraska, Arizona, New Mexico, Kansas, 

 Oklahoma, Texas; Galapagos Islands; Hawaiian Islands; Mexico; 

 Haiti; St. Vincent Island; Argentina. 



APUS LONGICAUDATUS LeConte 



Figures 3-6, 19, d, 29-31: Plates 5 (Figures 2, 3), 6, and 7 (Figures 1, 2) 



Apus longicaudatus LeConte, 1846, p. 274. — Packard, 1883, p. 324. — Mackin, 



1939, p. 46. 

 Apus aequalis Packard, 1871, p. 3; 1883, p. 320.— Pearse, 1912, p. 192; 1913, p. 2. 

 Apus newberryi Packard, 1871, p. 2; 1883, p. 321. 

 Apus lucasanus Packard, 1871, p. 2; 1883, p. 322, 

 Apus oryzaphagus Rosenberg, 1947, p. 70. 

 Apus biggsi Rosenberg, 1947, p. 72. 



As far as I can see, the various species of Apus described from the 

 North American continent must be united into one species, A. longi- 

 caudatus. A study of reasonably extensive material shows that the 

 thi'ee species of Packard, enumerated above, cannot be properly de- 

 marcated from each other and from A. longicaudatus, and the same 

 applies to Rosenberg's species. 



Packard's material was probably too limited to enable him to detect 

 the unbroken series of variation in most of the characters used by him. 

 It was not so much that he had material from so few localities — 

 4 species from 13 localities — as that only a few specimens were avail- 

 able from each locality. One of his species, A. newberryi, was based 

 upon three females from two localities. 



