﻿PYCNOGONIDA. 



onal legs to the pairs of limbs found in the imago. In the genus Pycnogonum the first pair of ambu- 

 latory legs, according to this, would be called Extrem. VI, the first five pairs of limbs having to be 

 subtracted. 



The foregoing list and figure apply to the grown larva, the young, and the imago; with 

 regard to the voung larva the following short list together with the figure of this larva, seen from 



the under side, must suffice. 



a. Cheliforus. 



b. First pair of embryonal legs. 



c. Second pair of eriibn,'Oual legs. 



d. Proboscis. 



e. First pair of ambulatory legs. 



f. Second pair of ambulatorj- legs. 



Fig. 2. Nymplwn robiistiim. Lar\'a. 



I shall now proceed to notice the outer organs, giving a short description of each as well as 

 the reason of the terms I have chosen, and at the same time I shall cjnote as synonyms the corre- 

 sponding appellations b}- the chief earlier authors. 



Proboscis [rostrum), fig. i ;•, and 2 (/. 



O. Fabricius: tubulus v. rostrum ; Latreille: tuyau ou siphon d'une seide piece; later (Regn. 

 anim. ed. II): bouclie; Leach: os tubulosum, or rostrum; Savigny: premier anneau du corps allonge 

 et remplagant la tete (vestiges de machoires); Johnston: rostrum; Milne- Ed wards: tete; Erich- 

 son: Zunge; Kroyer: Nceb (in the larva), later: Snabel (rostrum); Wilson: proboscis, or rostrum; 

 Dohrn: Schnabel; Bohm: Rostrum; Hoek: trompe (probcscis); Adlerz: snabel; Hansen: Snabel, 

 or Proboscis (proboscis); Sars: Snabel (proboscis), or ]\Iundsegment. 



The proboscis is the conical or almost cylindrical organ protruding from the anterior margin 

 of the body, or from the lower side of it; it is always large or especially so in proportion to the body, 

 and has at the point a trilobate mouth, leading to the trilateral pipe, which is closed behind Ijy a 

 kind of plait, protruding to a rather sharp angle and working as a filtering apparatu.s. The pro- 

 boscis is commenced at a very early stage of the embryonal life (pi. i , fig- i) as a ball or tubercle 

 without any trace of mouth, contemporary with the embr\onal limbs (the chelifori and embr\-onal 

 legs). It is no segment or metamere, and still less corresponding to, what in other aninuds is called 

 the head, or to part of the head. Neither can it in any way be supposed to have ari.sen by a coal- 

 escing of gnathites. 



First segment of trunk (srgiiioitiiiii corporis primu))i\ fig. i '"'. 



O. Fabricius: caput et thora.x v. primus arliculus corporis; Leach: segmentum anticum; 

 Latreille (Regn. an. ed. II): le premier segment du tronc; Joliuston: the anterior .segment of 

 thorax; Erichson: Kopf; Kroyer: Oiering og forstc Ihystring (anuulus ocularis el annulus thora- 



