440 THE AMERICAN NATURALIST. [Vor. XXXIX. 
Body rather slender; 10 to 25 mm. in length ; color yellow ; blood vessels 
deep red in color; basis and stylet both very slender and of about 
3009020» 
equal len 4 : : . A. cruentatus Verrill, C, S, X. 
Ocelli scattered, and not in a single row on each side of hea 5. 
Central stylet as long as basis, or considerably longer  . A ae, 
Central stylet considerably shorter than basis . i : A cz Mb 
Central stylet and basis of about equal length Ä à : E i 
. Central stylet about twice as long as basis — . : : i T £ 
. Body rather broad and flattened ; orange, brownish, or reddish above, 
with 2 large dark brown or black elongated spots on head ; ventral sur- 

A B Ç 
Fic. 5.— Outlines of stylet apparatus. 
A, Amphiporus formidabilis, with 12 pouches of accessory stylets. 
B, A. Punctatulus, with 2 pouch f y stylets. 
C, A. impar isPinosus, with 3 pouches of y stylets. 


face pale orange or flesh-color ; sometimes with 4 pouches of accessory 
stylets ; stylets very slender; 14 or 16 proboscidial nerves; cerebral 
sense organs beside brain . ‘ . A. bimaculatus Coe, A, P, C. 
7. Body rather short and thick; mottled thickly with dark brown dots and 
A. punctatulus Coe, S (at surface). 
8. Cerebral sense organs in front of brain . : ; ; à . 9. 
8. Cerebral sense organs beside brain. 
Body short and broad ; color reddish or brownish above, pale beneath ; 
! In a single species (A. leptacanthus) belonging to this group the relative length 
of stylet and basis is as yet unknown, and the species is not included in this key. 
Color of body whitish, with tinge of yellow or brown; basis of central stylet 
remarkably slender, four or five times as iong as broad ; ocelli 16-24 in a single 
irregular cluster on each side of head. 
