2 THE VOYAGE OF H.M.S. CHALLENGER. 
Otho Fabricius (1780)! assigns to them the name Pycnogonwm proposed by 
Briinnich, and places the Cyamus ceti with them in the same genus. He believes them 
to be most closely allied to Crustaceans. 
J. C. Fabricius (1794)? places the two genera Pyenogonum and Nymphon along with 
Pediculus, Acarus, &e., in the eleventh class (the Antliata) of his entomological system. 
Lamarck (1801) ® gives the same genera (Pycnogonum and Nymphon) a place in the 
class of the Arachnida, order of the Palpistes, together with Bdella, Acarus, and Hydrachna. 
Savigny (1816) * proposes to place the Pycnogonida among the Crustacea, an opinion 
afterwards embraced by Milne-Edwards (1834)*’ and Johnston (1837). According to 
Johnston, Savigny arrived at this conclusion by a very ingenious analysis of their organs. 
He pointed out that the proboscis of the Pycnogonum is a head, whereas the mandibles, 
palpi, and ovigerous organs are merely modifications of the legs, so that the Pyenogonida, 
like the Crustaceans, really have seven pair of legs, &c. 
Johnston ° himself, taking the assertions of Savigny as decisive, disagrees with those 
naturalists who object to the Pycnogonids being placed among the Crustaceans on 
account of the great simplicity of their anatomy. With Milne-Edwards he considers the 
Pyenogonids, although imperfect and even degraded, as formed on the same general plan 
as that of all the numerous other animals rightly placed in the class Crustacea. 
There can be no doubt that Johnston’s publication is one of the most important 
in the history of the knowledge of the group. Johnston gives a very clear descrip- 
tion of the body of a Pyenogonid, fully discusses the systematic position of the order, 
proposes good characteristic marks for the genera, and enters into detailed descrip- 
tions of the species. The number of genera in his paper amounts to five (Nymphon, 
Pallene, Orithyia, Phoxichilus, Pycnogonum), each with one species, with the exception 
of the genus Nymphon, to which two species are assigned. 
Of the authors who come after Johnston, Milne-Edwards is the first to be mentioned. 
In the third volume of his Histoire naturelle des crustacés (1840), he gives a very short 
description of the body of a Pycnogonid, and enumerates, but without paying special 
attention to the group, the species and genera known to him. — Following Johnston as 
nearly as possible, he has the same five genera‘ and almost the same species. His descrip- 
tions are very insufficient ; his work derives importance only from the circumstance that 
he places—as I have already mentioned above—the Pycnogonids among the Crustaceans 
as a distinct order, viz., that of the Araneiformes. 
 Othonis Fabricii Fauna Groenlandica, Hafniz et Lipsie, 1780. 
* Joh. Christ. Fabricii Entomologia Systematica emendata et aucta, tom. iv., 1794. 
3 J. B. Lamarck.—Systime des animaux sans vertebres, 4 Paris, an. ix., 1801. 
* J. C. Savigny—Mémoires sur les animaux sans vertébres, premidre partie, 1816. 
° H. Milne-Edwards.—Histoire naturelle des Crustacés, tom, i.-iii., 1834-40. 
® In this introduction only the most important authors are meuupcele a much fuller list is given by J obnston i in 
his An Attempt, &c., and by Milne-Edwards, loc. cit. 
7 The name Orith, yia of Johnston “ étant déja employé pour un autre genre de Crustacé,” is changed by Milne iaceneede 
into Phoxichilidiumd|.c., p. 535). 
