DESCRIPTION OP GENERA AND SPECIES. 273 



what procurved, almost aligned ; the rear row decidedly recurved. The clypeus is compara- 

 tively low. The abdomen is a long ovate, in the typical species U. plumipes marked by 

 shoulder humps ; the dorsum arched, the spinnerets distal, with an additional spinning 

 organ known as a cribellum. The legs are in length, 1,4,2,3, the first leg especially stout, 

 and, in all but the two final joints, relatively much more so than the other legs; the apex 

 of the tibia is marked in some species by a slight scopula or brushlike cluster of bristles. 

 The tibia of leg-IV is provided with a calamistrum in the female. Only one species 

 appears to be common in the United States ; but one other, U. geniculatus (zosisl, has at 

 least a lodging place upon the Gulf Coast. The snare of the species is an orb web, without 

 the ordinary viscid armature, for which is substituted the curled threads-'characteristic of 

 Hyptiotes and certain Clubionidae. 



No. 120. Uloborus geniculatus (Oliver). Plate XXVII, Figs, l, 2. 



1789. Aranem geniculatus, Oliver . . . Encycl. Method., ii., p. 214. 



1842. Ulobonis zosis, Walckenakr . . Apt. Ins., ii., p. 231, pi. xx.. Figs. 1, 2. 



1858. Uloborus Latreillei, Thorell . . Vet. Akad. Forh., xv., p. 197. 



1858. Orithyia )yilliami, Bl.\ckwall . . Ann. Mag. Nat. Hist., 3d ser., iii., p. 331. 



1859. Ulobonis domeslicus, Doleschal . Act. Soc. Sc. Ind. Neerl., v., p. 46, vii., 2. 

 1864. Uloborus borbonicus, Vinson . . Aran. Eeunion, etc., p. 258, i., 3. 



1872. Uloborus zosis, Koch, L Arach. Austral., p. 221, pi. xix., 3. 



1873. Uloborus zosis, Thorell .... Rag. Mai., etc., ii., p. 130. 

 1889,. Uloborus zosis, Mahx Catalogue, p. 554. 



1889. Uloborus geniculatus, Simon . . . Ann. Soc. Entom. France, p. 131. 

 1889. Uloborus zosis, Marx Proceed. Acad. Nat. Sci., Phila., p. 99. 



Female : Total length, 7 mm. ; cephalothorax, 3 mm. long, 2 mm. wide ; abdomen, 

 5 mm. long, 3.5 mm. wide. 



Cephalothorax: Cordate, truncated, deeply indented at the base, rounded at the 

 margins of the corselet, and nearly as wide in the anterior as in the posterior part; 

 corselet well arched, but somewhat flattened on top ; fosse a conical pit ; corselet grooves 

 distinct; cephalic suture well marked; color yellow, with patches of brown on either side 

 of the face, and at base of caput ; head wide, somewhat quadrate, slightly elevated above 

 corselet. Sternum (lb) much longer than wide, of about equal width throughout, except at 

 the apex; rounded in the middle; dull yellow, covered with yellowish gray hairs; labium 

 about half the length of the maxillse, narrow, subtriangular ; maxillae somewhat longer than 

 wide, the tips compressed into an elongated triangle, and directed toward each other; color 

 brown at the base, with yellowish tips. 



Eyes : (la.) Ocular quad much wider behind than in front, and the length somewhat 

 greater than the rear width; a slight longitudinal cleft separates the midfront eyes, which 

 are removed from one another by about a diameter or less ; MR somewhat less than MF, 

 separated by 1.5 to 2 diameters ; side eyes widely separated, the space between tliem as 

 great as that between MR and MF, which is equal to 1.3 the area of MF, or more than 

 twice the intervening space ; the distance between SR and MR about equals that between 

 MR ; clypeus somewhat higher than area MF ; front eye row procurved, the longer rear row 

 slightly recurved. The face is wide in front. 



Legs: 1, 2, 4, 3; femora and tibia stout, but the two apical joints greatly diminished 

 in size ; color yellow, with broad apical annuli ; abundantly covered with gray and brown 

 bristles and hairs, and with short, dark spines ; the metatarsus of leg-IV is curved, and 

 provided on the inner and upper side with a calamistrum (Id). 



Abdomen : Ovate, wide and rounded at the base, much narrowed towards the spin- 

 nerets, which are distal ; color ashen brown or yellow, without any decided folium ; the 

 epigynum (Ic) is without a scapus, and the thick, low atriolum has two short subtriangular 

 projections, which are bowl shape or hollowed underneath. 



