442 THE AMERICAN NATURALIST. [Vor. XXXIX. 
Body small, slender, rounded ; brownish, with minute dark brown dots ; 
25 or more ocelli; basis of central stylet bell-shaped ; cerebral sense 
organs large, situated close in front of brain . A. fulvus Coe, S 
14. Central stylet not more than half as long as basis : 15. 
15. Central stylet about half as long as basis. 
Body rounded, rather slender; color of females yellowish orange, ob. 
scured in intestinal region by dark green ova in breeding season ; 
males yellowish, with white flecks ; basis massive, rounded posteriorly ; 
cerebral sense organs in front of brain ; . A. tigrinus Coe, P. 
15. Central stylet about one third as long as the remarkably massive basis. 
Body short and rounded ; proboscis remarkably large, provided with 10 
nerves ; basis larger than in any other known species, measuring about 
a millimeter in length and easily visible to the unaided eye; stylets 
short and conical x : : 1. macracanthus Coe, N. 




: A B ra D E 
Fic. 7.— Outlines of central stylets and bases, 
i ; midabilis. D,A 
B, A. functatulus, E, A. flavescens. 
C, A. leßtacanthus, F, A. macracanthus. 
16. With 3 pouches of accessory stylets. ; 
White ; body slender ; ocelli usually less than 40; commonly 4 to 8 neph- 
ridiopores on each side, some of which are situated on dorsal side of 
body . - ; i € A. imparispinosus Coe, B, A, P, C, S. 
16. With 4 or more pouches of accessory stylets ; . . 17. 
17. With 4 (or sometimes 2) pouches of accessory styles. . . 18. 
17. With 6 to 12 pouches of accessory stylets. 
Body very slender ; color whitish or flesh-color ; ocelli usually 60 to 250; 
commonly 20 or more nephridiopores on each side, most of which are 
situated on dorsal side of body . A. formidabilis Coe, B, A, P, C. 
18. Orange, brownish, or reddish above, with 2 large dark brown or black 
