﻿NORTH AMERICAN NOTOSTRACA — ^LINDER 61 



were sent to the Stockholm Museum show the patterns of tltree of his 

 species. I have not found any correlation between any one pattern 

 and other characters. 



One feature considered here, in a limited way only, is the presence of 

 spines at the dorsal hind margin of the telson. Two spines should be 

 characteristic of A. longicaudattis. Even in this respect there is often 

 a great variation (fig. 30). Sometimes there are a number of small 

 spines on this margin, sometimes only a few or none at all, and in 

 some specunens we find two relatively large spines placed near the 

 midline. We notice that such spines occur not only in the pattern 

 said by Packard to be characteristic of A. longicaudatus, but also in 

 one which, as far as the central spines are concerned, is given for A. 

 lucasanus. Here, too, I have looked in vain for correlation with other 

 characters. 



I I I I I 



I I.I I I I 



M I i_L Li M' LM ^^ 



Number of specimens 2 12 2 1 11 



Figure 30. — Patterns of dorsal central spines and spines on dorsal hind margin of the 

 telson in specimens of Apus longicaudatus LeConte, from California {A. oryzaphagus 

 Rosenberg and A. biggsi Rosenberg). Abbreviations as in figure 29. 



Extra-American species of the genus, too, present great variation 

 in the spines on the telson. Often it is even greater than in American 

 species, as I have found in A. australiensis and A. granarius. Barnard 

 (1929) arrived at the conclusion that the presence, absence, or varying 

 degree of development of the central spines is of no taxonomic 

 significance in South African forms. 



Summing up, I have found that the main characters used by Packard 

 when describing his species of Apus are in part wholly unreliable and 

 in part subject to considerable variation without any clear correspond- 

 ence to other characters. Further, intermediate forms occur very 

 often. 



I have examined Packard's type specimens in the U. S. National 

 Museum and also paratypes of A. lucasanus in the Stockholm Museum. 

 Some of their characters are given in table 7. The variations in the 

 number of legless rings and the armature of spines on the telson of 

 A. lucasanus are aheady accounted for, and we learn from this that 

 Packard did not pay any attention to the presence or absence of 

 spines on the carapace and its carina. I quite agree with him that 

 this character is of no taxonomic significance. Further, we notice 

 from table 7 that the male of A. aequalis has two spines at the hind 

 margin of the telson, a character given by him for A. longicaudatus. 



