210 NATHAN BANKS. 



The Tronibidoidea are readily recognized by the fact that the last 

 joint of the palpus forms an appendage or thumb ; the penultimate 

 joint ending in a claw. One genus (AcUneda) aj)parently lacks this 

 appendage, but its general a])pearance readily places it in the proper 

 ftimily. The characters to observe in the separation of the species 

 in this super-family are as follows : the vestiture, shape and length 

 of the hairs, the fora) of the palpus and its appendage, the length 

 of the legs, and especially the form and size of the last joint of the 

 first pair of legs ; finally the color and form of the body and special 

 structures. We have five families of the Tronibidoidea, which may 

 be separated as follows : 



1. — Palpi very proniinoiit, and nnu-h thickened at base, mandibles styliform. no 



eyes, body naked CHEYLETID^. 



Palpi not prominent, nor greatly thickened at base, mandibles uncinate or 



styliform, usually with eyes 2. 



2. — The posterior and anterior pairs of legs close together, not tliickly clothed 



with hairs ERYTHRyETD^. 



The posterior pairs of legs arise some distance behind the anteiior pairs. ...3. 

 3. — With a mediuu dorsal groove, or else with six eyes, no prominent distinction 

 between cephalothorax and abdomen, eyes all sessile. 



EHY^'COLOPHID.E. 



No such groove above, only four eyes 4. 



4. — Large, thickly clothed with hairs, abdomen much elevated above the cephii- 



lothorax, eyes stalked, free when adult, not spinning TROMBIDIDJ<^. 



Small, bare or sparsely clothed with hairs, spinning mites, eyes sessile, para- 

 sitic on plants TETRANYCHID.E. 



The Erythrseidte have two genera represented in our fauna: 



Appendage to palpus present Ery tlir<eiis. 



Appendage apparently absent Ac'tiiieda. 



ERYTHR.EUS Latr. 



The body is somewhat divided into two portions; the legs are 

 long, and the body and legs both armed with long stiff hairs or 

 bristles. Palj)i five-jointed, the last joint forming an appendage. 

 Eyes present ; they are very brightly colored, usually with red, and 

 move very rapidly. 



Say described one species from Georgia and Florida, Erythneus 



mamillatus. It is unknown to me. A species I have collected a few 



times about houses and barns may be known as 



Erytlira'US spiiiatiis nov. sp.— Length 1. mm. Color bright j-eddish, 

 eyes lilack, a more prominent red spot between the eyes, abdomen dark in center 

 jirobably from food. Body oblong, pointed behind, showing two constrictions in 

 front of the middle, the first between legs ii and iii, the second above leg iv. 



