258 COLE 



KEY TO THE SPECIES 



The following key is adapted only to the species of Pycno- 

 gonida described in this paper, and is applicable only to adult 

 forms. If a chelate specimen not positively known to be adult 

 cannot be identified by it, the specimen may be an immature in- 

 dividual and can perhaps be traced by considering it under A, 

 forms with " Chelifori present, not chelate in adult." 



A. Chelifori present, not chelate in adult; palpi present; ovigera 10- 



jointed, present in both sexes (AMMOTHEID^}. 



B. Body rather elongate, distinctly segmented ; lateral processes well 

 separated; chelifori i -jointed; palpi g-jointed (Lecythorhyn- 

 chus]. 

 C. Proboscis subcylindrical or elliptical, constricted in its middle 



third Lecythorhynchus marginatus, p. 260 



B 7 . Body more or less discif orm ; segmentation often indistinct ; lateral 



processes approximated. 



C. Chelifori 2- or 3-jointed ; palpi 8- or Q-jointed. 

 D. Chelifori 2-jointed ; palpi 8-jointed (Ammothea). 



E. Chelifori more than half as long as proboscis ; caudal seg- 

 ment reaching at least to middle of second coxal joint of 

 fourth pair of legs .... Ammothea latifrons, p. 263 

 E 7 . Chelifori less than half as long as proboscis. 



F. Proboscis narrow, fusiform; forms less than 4 mm. in 



length and 20 mm. in extent. 



G. Protuberance on dorsal side of first coxal joint about 

 half as long as the joint ; genital protuberance in 

 male of about the same length. 



Ammothea alaskensis, p. 266 



G 7 . Protuberance on dorsal side of first coxal joint fully 

 three fourths as long as the joint; genital protu- 

 berance in $ only about half as long as protuberance 

 on first coxal joint . . Ammothea gradlipes, p. 269 

 F 7 . Proboscis broadly clavate, truncate at the apex ; forms 

 over 4 mm. in length and 20 mm. in extent. 



Ammothea pribilofensis, p. 270 

 D 7 . Chelifori 3-jointed ; palpi g-jointed (Ammothella}. 



E. Eye tubercle low, rounded; first 2 or 3 trunk segments 



with a conical tubercle dorsally near the posterior border. 



Ammothella tuberculata, p. 273 



E 7 . Eye tubercle tall, slender ; caudal segment slender, curved, 

 elevated, spinose ; first and second trunk segments with 

 a pair of spines dorsally near the posterior border. 



Ammothella spinifera, p. 275 



C 7 . Chelifori usually i-, sometimes 2-jointed; palpi 6- or 7-jointed. 

 (Tanystylum}. 



