5 26 PYCNOGONIDA 



this unimportant numerical coincidence ; nor is there any signifi- 

 cance in the apparent outward resemblance to isolated forms (e.g. 

 Cyamus) that induced some of the older writers, from Fabricius 

 downwards and including Kroyer and the elder Milne-Edwards, 

 to connect tlie Pycnogons with the Crustacea. To refer them, 

 or to approximate them to the Arachnids, has been a stronger 

 and a more lasting tendency.^ Linnaeus (1767) included the 

 two species of which he was cognisant in the genus Phalangiuvi, 

 together with P. opilio. Lamarck, who first formulated the 

 group Arachnida (1802), let it embrace the Pycnogons; and 

 Latreille (1804, 1810), who immediately followed him, defined 

 more clearly the Pycnogonida as a subdivision of the greater 

 group, side by side with the subdivision that corresponds to our 

 modern Arachnida (" Arachnides aceres "), and together with a 

 medley of lower Crustacea, Alyriapoda, Thysanura, and Parasitic 

 Insects ; he was so cautious as to add " j'observerai seulement, 

 que je ne connais pas encore bien la place naturelle des Pycno- 

 gonides et des Parasites," and Cuvier, setting them in a similar 

 position, adds a similar qualification." 



Leacli (1814), whose great service it was to dissociate the 

 Edriophtlialmata and the Myriapoda from the Latreillian medley, 

 left the group Arachnida as we still have it (save for the inclusion 

 of the Dipterous Insect Nyctcrihia), and divided the group (with 

 the same exception) into four Orders of which the Podosomata, i.e. 

 the Pycnogonida, are one. Savigny (1816), less philosophical in 

 this case than was his wont, assumed the Crustacean type to pass 

 to the Arachnid an by a loss of several anterior pairs of appen- 

 dages, and appears to set the Pycnogons in an intermediate grade, 

 marking the pathw^ay of the change. He considered the seven 

 pairs of limbs of the Pycnogons to represent thoracic limbs of a 

 Malacostracan, and, like so many of his contemporaries, was much 

 biased by the apparent resemblance of Cyamus to Pycnogonum. 

 The reader may find in Dohrn's Monograph a guide to many 

 other opinions and judgments, some of them of no small morpho- 

 logical interest and historical value ^ ; but it behoves us to pass 



^ Cf. Carpenter, Proc. R. Irish Acad, xxiv., 1903, p. 320 : Lankester, Quart. 

 J. Micr. Sci. xlviii., 1904, p. 223; Bouvier, Exp. Antard. Fr., " Pycnogonides," 

 1907, p. 7, etc. 



2 "Nous lie les pla^ons ici qu'avec doute," Rtgne Anim. ed. 3, torn. vi. 

 p. 298. 



^ Cf. also J. E. W. Ilile, " Phylogeiiie und systeniatische Stellung der Panto- 



