10-i BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



aa- Body with only a modei-ate amount of parenchyma. b. 



b. Esophagus provided with large caecum extending on 

 ventral side of esophagus proper and ending blindly 

 posteriorly- 



1. Esophageal caecum extends posteriorly far beyond 



anterior ends of intestinal caeca ; body paren- 

 chyma but little developed ; ocelli numerous. 



A. occidentalism p. 271. 



2. Esophageal caecum terminates posteriorly in front 



of anterior ends of intestinal caeca; body paren- 

 chyma comparatively well developed; ocelli few. 



A. rubeUus, p. 274. 

 bb. Esophagus without ventral caecum . . . c. 



c . Proboscis provided with more than 2 pouches of acces- 

 sory stylets. 



1. With o 1 touches of accessory stylets ; color white, 



body slender, ocelli usually less than 40. 



A. ijnparispinosus, p. 247. 



2. With (J to 12 pouches of accessory stylets ; body very 



slender ; color whitish or flesh color ; ocelli usually 

 60 to 250 . . .A. formidabilis, p. 2.50. 



3. With 2' or 4 pouches of accessory stylets ; body broad 



and flat ; color orange, brownish, or reddish above, 

 with 2 large dark brown or black angular spots 

 on head ; ventral surface pale orange or flesh 

 color; 14 or 16 proboscidial nerves. 



A. hiinnculatus, y>. 241. 



4. Occasionally witli 4 pouches of accessory stylets; 



dark In-own or purplish, with small, angular 

 white spot on each side of head ; A'entral surface 

 pink or flesh color; 17 to 20 proboscidial nerves. 



A. angulatus, p. 238. 



cc. Proboscis usually provided with only two pouclies of 



accessory stylets . . . . . . d. 



d. Ocelli in a single row on each side of head. 



1. Body rather slender; 10 to 25 mm. in length; 



color yellow; blood corjiuscles deep red in color ; 



basis and stylet both very slender and of about 



equal length . .A. cruentatus, p. 24(5. 



dd. Ocelli scattered, and not in a single row on each 



side of head i . . . . . . e. 



1 In a sino'le species (^4. leptaranthus, p. 279) belonging to this group, the 

 relative length of stylet and basis is as yet unknown, and the species is there- 

 fore not included in this key. 



