78 TERTIARY INSECTS OF NORTH AMERICA. 



circle. The legs, of ^yllicll only the third and fourth pairs are j^erfect, are 

 very long, excepting the third pair; the femora and perhaps the tibife have a 

 superior series of alternately diverging, slender, very distant spines, farther 

 from one another than their own lengths. The abdomen is long obovate, 

 subcylindrical, a little the largest at tlie base, as long as the ceplialothorax 

 and cheliceres together. 



Lengtli of body, 10"""; of abdomen, 5"""; breadth of ceplialothorax, 

 2.5"""; of abdomen, 2.3"""; length of mandibles, 3.2"'"'; breadth of the basal 

 portion, 0.7"""; of the apical portion, 1.3"""; greatest diameter of last palpal 

 joint, 1.25"'"'; least diameter of .same, 1.15"'"'; length of femora of iirst i)air 

 of legs, S-TS'"""; of second, T'""; of third, 3.5'"'"; of fourth, T"""; length of 

 third pair of legs, 9.5""'; of fourth pair, 18.5'"'". 



Florissant. One S, Nos. 5000 and 5898. 



TETHNEUS, gen. nov. {©ytjouco). 



Under this name are here grouped several evidently nearly allied spe- 

 cies of spiders, which closely resemble in general aspect those placed under 

 Epeira, but which differ also from them in certain features, and in these 

 same characteristics appear to differ also from all other Epeirides, to which 

 family they evidently belong. They are compact in form, with short and 

 stout legs of not very unequal length, and in particular the first two pairs 

 of legs are unusually heavy. The second and fourth pairs of legs are of 

 nearly equal length, or the second pair may be slightly longer; the femora 

 of the first and second pairs of legs are at base as broad as or even broader 

 than half the width of the ceplialothorax, and the longest legs are less, gen- 

 erally considerably less, than twice as long as the body. The species are 

 of medium size. 



TrtftJe of the species of Tcthiieiis. 



Cephalic aud thoracic jiortious of the corselet .separated by a distinct rectangular incision. 



Last palpal joint of male globose 1. T. (juyoti. 



Last palpal joint of male elongated 4. 7'. provcetus. 



No line of demarkation between the two parts of the cor.selet. 



Smaller species, cephalothorax regularly obovate 2. T. obduratua. 



Larger species, cephalothorax ovate, nearly pyriform 3. T. henizii. 



1. Tethneus GUYOTI. 

 PI. 11, Figs. 8 ( 3 ), 10 ( 9 ). 



Oephalotliorax roundly obovate, not much longer than l)road, broadest 

 Ijehind the middle, the cephalic separated from the tlioi-aeie portion by a 

 deep incision, reaching nearly to the middle of the whole section ; and behind 



