372 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. t 
Hitherto then the Pycnogonidse appear to have been considered 
as insects nearly allied to the mites and spiders. Otho Fabriciushad 
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 ta alter the usual location of these animals 
excepting Milne Edwards, 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 Pycnogonidse 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. 305. Lond. 1819. 
\ Faun. Groenl. 229.* 
Risso scarcely affords an exception. He places the genus Nymphon 
amongst the Lemodipodous crustaceans, next to Caprella ! Hist. Nat. de 
1'Europ. Merid. v. p. 102. 
