5 26 PYCNOGONIDA 



this tinimportant numerical coincidence ; nor is there any signifi- 

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

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

 downwards and including Kroyer and the elder Milne-Edwards, 

 to connect the 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 Phcdangium, 

 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, Myriapoda, 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.^ 



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

 Edriophthalmata and the Myriapoda from the Latreillian medley, 

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

 of the Dipterous Insect Kycterihia), 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 x^ass 

 to the Arachnidan by a loss of several anterior pairs of appen- 

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

 marking the pathway 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 Gyamus 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. It. Irish Acad, xxiv., 190.3, p. 320 ; Lankester, Quart. 

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

 1907, p. 7, etc. 



^ "Nous ne les pla^ons ici qu'avec doute," Eigne Anim. ed. 3, torn. vi. 

 p. 298. 



' Cf. also J. E. W. Ihle, "Phylogenie und systematisohe Stellung der Panto- 



