292 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



confinis Berlese as reexamined by Tuxen (1956a). The broad a' 

 seems to be very characteristic of this species. 



The chaetotaxy is exactly like that of confinis; therefore, we shall 

 not give it in detail. Also the shape of the apodemes is the same. 



The comb of abd. VIII (fig. 68) is drawn from one of the specimens 

 on the type slide, because it seems to be a little different from that of 

 confinis. There are the same number of teeth, about 12, but Tuxen 

 (1956a, p. 232) states that one of the central teeth of confinis is longer 

 than the rest; this condition is not so in christensoni. We do not, 

 however, consider this difference important. 



The head (fig. 69) is drawn by Bonet from a specimen on the type 

 slide; it is a typical Acerentulus head. 



The filamento di sostegno is exactly like that of confinis. 



Thus we conclude that Acerentomon christensoni is identical with 

 Acerentulus confinis Berlese and should be lowered to the rank of a 

 synonym. 



Acerentomon occidentalis Ewing 



Figures 70-76 

 Acerentomon occidentalis Ewing, 1940, p. 540. 



There are three slides present of this species, the holotype and two 

 paratypes. All three specimens are females and bear the data, 

 floor of Yosemite Valley, California, in decaying leaves and twigs, 

 April 15, 1927, H. E. Ewing collector. Our drawings are from the 

 holotype and one paratype. 



The foretarsus (figs. 70-71) is extremely broad and short compared 

 with the foretarsi of other acerentomids known to us. The ratio of 

 the claw to the rest of the tarsus is 53: 150, i.e., nearly 1 :3; in Aceren- 

 tulus americanus, for instance, it is 32:105, i.e., 1:3.5; this ratio is 

 more common. Also the ratio of breadth to length of foretarsus 

 (without pretarsus) is 45:140, about 1:3; in americanus it is 20:100 

 or 1:5, as is more or less the case in the other species. This ratio, 

 however, is only discernible if the specimen is seen from the side, not 

 from above or below. The t 1 is long and slender, not clavate, placed 

 exactly in the middle of the tarsus; d:p = 70:70. The t 3 is long, 

 lancet shaped; b is much longer than c; d and f are long, e and g short. 

 On the interior side a' is missing; b' is a little broader and shorter 

 than c'. 



