8 PYCNOGONIDA. 



next introduced the expression pollex (i. e. thumb) for this process, though this latter name had already 

 been used by O. Fabricius and Kroyer of the last joint of the cheliforus, the movable finger. 



Movable finger (pollex v. digitus mobilis\ fig. i dm. 



O. Fabricius: pollex; Kroyer: Tommel (pollex); Hoek: griff e mobile des mandibules; 

 Wilson: dactylus; B0hm: Scheerenfinger or Daumeii; Han sen: Index; Sars: bevaegelige Finger 

 (dactylus). 



I have kept the old name of O. Fabricius and Kr0yer pollex or movable finger for the 

 terminal joint of the cheliforus, or the movable finger of the hand, and can see no reason to intro- 

 duce instead of it the dactylus of Wilson. 



To avoid every misconception it would perhaps be best to omit the use of the short names of 

 pollex, dactylus, index, and thumb, and to abide by the appellations digitus immobilis and digitus 

 mobilis, immovable and movable finger, as I have done in the synoptical figure by choosing the 

 letters dim and dm. 



Ambulatory leg (pes ambnlatorius), fig. i pa and 2 e,f. 



Schimkewitsch, Pantop. Vettor Pisani, gives to the first pair of ambulatory legs also the 

 separate name: Patte-machoire. 



The rise and development of the four pairs of ambulatory legs follow the larval development, 

 and they are never wanting in the imago, nor reduced in any way but at most by the defective devel- 

 opment or the falling off of the claws or the auxiliary claws. They arise from the ends of the lateral 

 processes of the body, and are, to judge from the rudiments in the embryo and the larva, as has been 

 mentioned, only prolongations of these processes, constricted into the number of nine joints, inclusive 

 of the claw, which is common to all Pycnogonida. 



First coxal joint (articulus coxalis primus), fig. i c 1 . 



Second coxal joint (articidus coxalis secundus), fig. i c 2 . 



Third coxal joint (articulus coxalis tcrtius), fig. i c?>. 



Sars: 3 Hofteled (articuli coxales). 



These three joints form the proximal end of the ambulatory leg; they belong to the shortest 

 joints of the leg, and form a series of homonomous joints, being of one set; therefore they may all 

 together correctly be termed the coxa. 



Femoral joint (femur), fig. if. 



Sars: Laarled (articulus femoralis). 



In the Arthropoda, especially the Insects, the femoral joint follows upon the coxa and coxal 

 segment or trochanter, which in these animals is only a subordinate joint. I think it, however, im- 

 possible to transfer the terminology of the legs of the Insects to those of the Pycnogonida, and there- 

 fore I have considered it advisable to follow Sars in his appellations of the joints of the leg, only 

 with some variation in the special names. 



First tibial joint (articulus tibialis prior\ fig. i tb*. 



Second tibial joint (articulus tibialis alter), fig. i tb 2 . 



Sars: Lsegled (articuli tibiales). 



These two joints of the leg are closely united, and there is no reason to give any prominence 



