OF WASHINGTON. 251) 



it is manifestly illogical to associate with either of them a family 

 which has not even entered upon similar development. The 

 maxillae of Hubbardia are still almost unmodified legs compared 

 with those of either Thelyphonus or Tarantula. They stand in 

 the vertical rather than in the horizontal plane ; the claw is not 

 coalesced with the distal joint ; the joints are none of them truly 

 opposable, and the armature is very slight and offers no evident 

 homology to that of either Thelyphonus or Tarantula. Agree 

 ments and differences in other characters do not seriously affect 

 the case, since there is no evidence to prove that the Hubbardiidoe 

 are degenerate Tarantulidae or Thelyphonidae. The segmented 

 cephalothorax once coalesced could not be expected to redivide, 

 and the maxillae once rendered effective by specialization would 

 scarcely return to the primitive and undifferentiated condition of 

 the ambulatory leg. 



The Pedipalpi consist, then, if Koenenia be included, of four very 

 natural and compact groups of animals which by their diversity 

 of structure and developmental history demand recognition as of 

 more than family rank. With reference to the anterior appen 

 dages alone these groups may be distinguished as follows : 



Second and third pair of thoracic appendages ambulatory in structure 

 and function, and provided with three-pronged claws : Order Micro- 

 thelyphonida, family Koeneniidae.* 



Second appendage modified to assist in feeding, and provided with a 

 simple claw; third pair of appendages modified into tactile organs, with 

 out claws 



Second pair of appendages vertical, with a movable claw: Order 

 Colopyga. 



Second pair of appendages horizontal, the claw immovably soldered to 

 the last joint 



Second pair of appendages adnate at base ; last joint with a vertical mo 

 tion permitting opposition with a process of the preceding; other joints 

 not opposable ; third pair of appendages with a Q-jointed tactile flagellum : 

 Order Uropyga. 



Second pair of appendages free at base ; last joint with a horizontal mo 

 tion, not opposed to the preceding; third and fourth joints closely op- 



* According to Grassi, his Koenenia mirabilis (Naturalista Siciliano, 

 1885, iv, p. 127), the palpi (maxillae, second appendages) are Q-jointed, the 

 cephalothorax is divided by two transverse sutures into three segments, 

 of which the last is narrowed to form a sort of peduncle for the distinct 

 abdomen ; the abdominal rings are ten in number, and are without lateral 

 sutures, and there is a long, slender, 13-jointed tail. Grassi bestowed the 

 name Microthelyphonida for the order, for which Thorell has proposed a 

 substitute in the form of " Palpigradi." 



