OF WASHINGTON. 257 



FAMILY HUBBAKDIID^E. 



Cephalothorax transversely divided into two or three sections of un 

 equal size, the third and fourth pairs of legs being attached to the posterior 

 portion. 



Ejes wanting or rudimentary. 



Maxillae 6-jointed, consisting of a coxa, trochanter, femur, a long patella, 

 tibia, and hand, the last not chelate. 



Flagellum of first pair of legs 8-jointed. 



Tarsi with three claws, two dorsal and one ventral. 



Abdominal appendage short, curved, or capitate, not jointed. 



If now we tabulate in similar form currently accepted charac 

 ters of the Tarantulidas, it appears that the points of similarity 

 between the Thelyphonidae and Tarantulidae are not less nume 

 rous than those which might be alleged between the Thely 

 phonidae and Hubbardiidae. 



FAMILY TARANTULIDAE. 



Cephalothorax of a single piece to which all four pairs of legs are at 

 tached. 



Eyes present in three widely separated clusters. 



Maxillae 5-jointed, consisting of coxa, trochanter, femur, tibia, and hand. 



Flagellum of first pair of legs many-jointed. 



Tarsi with two claws. 



Caudal appendage wanting. 



Formal ' characters ' like the preceding are, however, fre 

 quently of the slightest value as affecting conclusions regarding 

 phytogeny and systematic arrangement. 



Thus in the above comparisons I have followed Professor 

 Kraepelin's statements in regard to the maxillae. I believe, how 

 ever, that there is no very essential difference in the structure of 

 that member in the three families, and that six joints are in reality 

 present in all. It is easy to see that the large terminal claw of 

 the Tarantulidae is composed of two parts, the distal of which is 

 smooth, being the true claw, while the hairy proximal portion is 

 a somewhat reduced and strongly chitinized joint with which 

 the claw has become immovably coalesced. The movable finger 

 of the " hand " of the Thelyphonidae is also evidently a joint and 

 not a claw merely, so that Professor Kraepelin's intercalation of 

 a " long patella" into the maxilla of the Hubbardiidae seems un 

 warranted, unless the same joint is to be recognized elsewhere. 



the direction of the inferior claw may vary with regard to the axis of the 

 leg, but it is constant in regard to the other prongs of the claw. In 

 Thelyphonus, the inferior claw is shorter than in Hubbardia, while in 

 Tarantula it is reduced to a rounded prominence. 



