242 ROBERT h. wolcott: 



Acetabula 5 on each side 4. 



Acetabula more than 6 on each side 10. 



3. First pair of legs thicker than the palpi, 

 with movable spines set into the sides of 

 deeply excavated conical papillae, and with 



claws simply bifid 1. A. crassi-pes (Miill.) 



First pair of legs not so thick as palpi, with- 

 out movable spines, and with a broadly ex- 

 panded pectinate claw 2. A.pectinatus mihi. 



4. Legs very long, first pair thicker than palpi; 

 body truncate posteriorly and with a promi- 

 nent nipple-like papilla at either lateral 



posterior angle 3. A. aculeatus Koen. 



Legs shorter and first pair not so thick as 



palpi; body evenly rounded or emarginate 



behind 5. 



.5. Last pair of legs modified and posterior mar- 

 gin of the body emarginate 6. 



Last pair of legs not modified and posterior 



margin of the body rounded 7. 



6. Modification consisting of a curved fourth 

 segment on last pair of legs. Legs long 



and slender 4. A. intermedins Koen. , male. 



Modification consisting of a thickening of 

 the first four segments of the last pair of 

 legs, and a shortening of the fifth, which 

 bears two heavy spines, while the sixth is 

 long and slender. All legs stouter and 

 thicker 5. A. abrwrmipes mihi, male. 



7. Genital plate of each side divided into two 

 parts, with two and three acetabula re- 

 spectively 8. 



Genital plate on each side not distinctly di- 

 vided 9. 



8. Claw with two hooks nearly equal in length, 

 4. A. intermedins Koen. , female. 



