2 THE VOYAGE OF H.M.S. CHALLENGEE. 



Otho Fabricius (1780)^ assigns to tliem tlie name Pycnogonum proposed by 

 Briinnicli, and places the Cyainus ccti with them in the same genus. He believes them 

 to be most closely allied to Crustaceans. 



J. C. Fabricius (1794)^ places the two genera Pycnogomim and Nymjihon along with 

 Pedicidus, Acarus, &c., in the eleventh class (the Antliata) of his entomological system. 



Lamarck (1801) ^ gives the same genera {Pycnogonum and Nymjjhon) 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 theii- 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 Pycnogonida, 

 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 Pycuogonids being placed among the Crustaceans on 

 account of the great simplicity of their anatomy. With Milne-Edwards he considers the 

 Pycnogonids, 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 l^e 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 Pycnogonid, 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 numlier of genera in his paper amounts to five {Nymphon, 

 Pallene, Orithyia, Phoxichilus, Pycnogonum), each with one species, with the exception 

 of the genus NymiDhon, 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 crustaces (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 abeady mentioned above— the Pycnogonids among the Crustaceans 

 as a distinct order, viz., that of the Araneiformes. 



1 Othonis Fabricii Fauna Groenlandica, Hafnise et Lipsiw, 1780. 



= Joh. Christ. Fabricii Entomologia Systematica emendata et ancta, torn, iv,, 1794. 



* J. B. Lamarck.— Systems des animaux sans vertfebres, i Paris, an. ix., 1801. 



* J. C. Savigny.— Memoires snr les animaux sans vertfelires, premiere partie, 1816. 

 5 H. Milne-E(iwards.— Histoire naturelle des Crustaces, torn, i.-iii., 1834-40. 



« In this introduction only the most important authors are mentioned ; a much fuller list is given liy Johnston in 

 his An Attempt, &c., and by Milne-Edwards, loc. cit. 



' The name Orithyia of Johnston "etant dcjJi employ^ poiu' un autre genre de Cnistac^," is changed by Milne-Edwards 

 into Phoxichilidium (I.e., p. 535). 



