37*2 Miscellanea Zoologica. 



of mandibles. The names of the tribes were subsequently dropped, 

 and they assumed the rank of families, the former being called 

 Nymphonides, the latter Pycnogonides, while the ordinal name was 

 altered to " Podosomata," which, however, was still allowed to stand 

 amongst the Arachnides ;* but Dr Leach latterly became so per- 

 plexed with doubts and difficulties relative to this family's relation- 

 ship to other animals, that he dissevered it entirely from the sys- 

 tem, and threw them into an appendix. + 



Hitherto then the Pycnogonidee appear to have been considered 

 as insects nearly allied to the mites and spiders. Otho Fabricius had 

 long ago hinted that they were probably of nearer affinity to Crus- 

 taceans^ but the hint was forgotten until Savigny, by a very in- 

 genious analysis of their organs, arrived at the same conclusion : he 

 believes that they are the group by which nature passes from the 

 Crustacea to the exantennulate spiders, and belonging rather to the 

 former than the latter class. His opinion does not seem to have in- 

 duced any systematist to alter the usual location of these animals 

 excepting Milne Ed\vards,§ who has entirely embraced it, and acted 

 upon it. As the question is not one of mere convenience, for, ac- 

 cording as our decision is more or less consonant to nature, so will 

 our views be in reference to the distribution of the groups of these 

 classes, I will enter a little into the discussion. 



The reasons for arranging the Pycnogonidee with the Arachnides 

 appear to be these: — 1. The general resemblance they have to the 

 members of that class; 2. the absence of external branchiae ; 3. the 

 sameness in the number of legs ; 4. the similarity in the position, 

 structure, and arrangement of the eyes ; 5. the simplicity of their or- 

 ganization, more especially of the circulating system. At a first 

 glance these reasons are seemingly of great weight, but a narrow 

 examination may shew that they are unsatisfactory. There is per- 

 haps nothing more characteristic of the spiders than the great pro- 

 portionable size of the abdomen, and the coalescence of the thoracic 

 segments, but in the Pycnogonida the abdomen is reduced to its mi- 

 nimum, while the thorax is much enlarged, and consists of four dis- 

 tinct segments, so that the resemblance between them and some 

 Phalangia is evidently unreal and illusory. The absence of bran- 



* Linn. Trans, xi. 387. Lond. 1815. 



f Samouelle's Ent. Comp. 805. Lond. 1819. 



\ Faun. Grcenl. 229.* 



§ Risso scarcely affords an exception. He places the genus Nymphon 

 amongst the Lemodipodous crustaceans, next to Caprella ! — Hist. Nat. de 

 l'Europ. Merid. v. p. 102. 



