[485] ARACHNIDA 45 



tarsus I, nor in tibia II ; palpi with rows of denticles, the patella and 

 tibia on inner side swollen and there thickly clothed with short, erect 

 spine-like hairs, claw not toothed ; no supra-mandibular spine. Length 

 5 mm., femur II, 4 mm. 



Two from Popof Island (one not adult and not fully marked from 

 the mountain top). 



Type. Cat. no. 5272, U. S. National Museum. 



PSEUDOSCORPIONIDA. 



Ideobisium threveneti (Simon). 



Obisium threveneti SIMON, Ann. Soc. Entom. France, p. 156, 1878. 



Several examples from Cook Inlet, Lowe Inlet (June), Long Inlet, 

 Popof Island, and Yakutat. Known from California, Oregon and 

 Washington. 



ACARINA. 



Gamasus sp. 



Several specimens from Kadiak on a Necrophortis, and from Sitka ; 

 none in an adult condition, and no males. 



Holostaspis exilis sp. nov. Plate XXIX, fig. i. 



$ . Pale yellowish, the legs still paler. Body about twice as long 

 as broad, tapering each way, broadest before third legs, but slightly 

 convex above, clothed with scattered long, simple hairs, more numerous 

 at tip of body ; each side at posterior third of the dorsal shield is a 

 row of four or five round, reddish, impressed dots. Palpi slender ; 

 leg I slender, no claw nor sucker at tip ; leg II with fourth joint 

 thickened and with a large tooth below, and a small one above, the 

 sixth joint with a small tooth at base and a long blunt spine at tip ; 

 legs III with a spur on hind tip of second joint, and one below near 

 middle of third joint ; leg IV with the second joint swollen on an- 

 terior face, and just before tip with a long slender process ; bifid at 

 tip. The peritreme runs directly to the stigmata which are above the 

 third coxae. The sternal plate is very narrow behind, so that the hind 

 coxae are not separated by half their width. Length 2 mm. 



9 . What appears to be the female of this species is smaller, more 

 reddish, the abdomen broadly rounded behind, the hind coxa? are more 

 widely separated, yet much closer than third coxae, the legs are un- 

 armed ; the dorsal shield shows a slight incision near middle of each 

 side, indicating the division of the immature forms. Length 1.5 mm. 



Several specimens from Yakutat, Berg Bay, Sitka, and Popof Island. 



Type. Cat. no. 5273, U. S. National Museum. 



