PYCNOGONIDA. 



characteristic in contradistinction to the others, or when one or more pairs have disappeared, so that 

 Extrem. IV is to be understood, now as the first, now as the second, third, or fourth pair of the 

 Preserved limbs of the imago. The greatest drawback by Dohrn's way of designation is to me that 

 it does not at all agree with the developmental history, the embryonal legs (fig. 2 3, c) not being 

 included; and although they are not to be regarded as the predecessors of the two foremost pairs of 

 ambulatory legs (Kroyer), they are neither the predecessors of the second and third typical pairs of 

 limbs of the imago, the imagiiial fore-limbs, or of the palpi and the ovigerous legs. I hope that it 

 will appear from my examination of the larval development that these two pairs of limbs are not 

 predecessors of, or identical with, the embryonal legs, to which examination the reader is referred. 

 Now, if the embryonal legs are neither identical with the two first pairs of ambulatory legs (Kroyer), 

 nor with the palpi and ovigerous legs (Dohrn's Extrem. II and III), there will be typically 9, and 

 not 7, pairs of limbs, as supposed by Dohrn and all naturalists, excepting Semper, Pycnog. und 

 Larvenf., 1874 (who has 8 pairs). Even if it be supposed that the embryonal legs are peculiar limbs, 

 it would, of course, be possible to use the appellation of Dohrn, the list of limbs then only being 

 increased from VII to IX; but on the other hand it would be very untoward to be always obliged to 

 subtract several, sometimes more than the half, from the number, which is got by adding the embry- 



t,r 



pa,-- 



Fig. I. Nymphon Strocmii. 



r. Proboscis (rostrum). 



c*. First segment of trunk (segmentum corporis primum). 



a. Oculiferous tubercle (tuber oculare). 



cl. Neck (collum). 



apo. Lateral process of the first segment for the insertion 



of the ovigerous legs (protuberantia pedis oviferi). 



c 2 . Second segment of trunk (segmentum corporis secun- 



dum). 



a. Third segment of trunk (segmentum corporis' tertium). 



c4. Fourth segment of trunk (segmentum corporis quar- 



tum). 



sc. Caudal segment (segmentum caudale). 



pel. Lateral process of the body for the insertion of the 



ambulatory legs (processus corporis lateralis). 



chf. Cheliforus (cheliforus). 



j. Scape (scapus). 



cli. Chela, or Hand (chela v. manus). 



pint. Palm (palma). 



dim. Immovable finger (acumen v. digitus immobilis). 



dm. Movable finger (pollex v. digitus mobilis). 



pa. Ambulatory legs (pes ambulatoriusi. 



ex- 1 . First coxal joint | articulus coxalis primus). 



ex*. Second coxal joint (articulus coxalis secundus). 



cxl. Third coxal joint (articulus coxalis tertius). _ 



f. Femoral joint (femur). 



tt*. First tibial joint (articulus tibialis prior). 



tb 2 . Second tibial joint (articulus tibialis alter). 



ta l . First tarsal joint (articulus tarsalis priori. 



(a 2 . Second tarsal joint (articulus tarsalis alter). 



u. Claw (unguis). 



uo. Auxiliary claw (unguiculus auxiliaris). 



plj>. Palpus (palpus v. pes palpiformis). 



po. Ovigerous leg (pes ovifer). 



ptr. Terminal part of the ovigerous leg (pars terminalis 



pedis oviferi). 



glov. Egg-globe (globus ovoruni). 



