198 LEON J. COLE. 



in preventing pycnogonid larvae from being swept off the hydroids 

 by a swift tide. After metamorphosis the claws of the walking 

 legs are used for attachment, while the chelifores then probably 

 serve as feeding organs, as has been observed to be the case in 

 Anoplodactylus (Cole, 1906) and Phoxichilidium (Loman, 1907). 



It seems worth while to call the attention of any who might 

 care to investigate the embryology or anatomy of this group to 

 the advantages of this species should it continue to appear in 

 Vineyard Sound, where it is so readily accessible to the marine 

 laboratories at Woods Hole. During the seasons it was observed 

 all stages for a study of the embryology and later development 

 were present in great abundance, while owing to its transparency, 

 it is very favorable for observing the internal anatomy, as well 

 as some of the physiological functions of the living animal. The 

 peristaltic movements of the intestinal ceca in the legs are easily 

 discernible, and our knowledge of the circulation of the blood 

 in the pycnogonids has been derived largely from this species. 

 The passage of food through the intestine and the extrusion of 

 feces has been well described by Loman (1907) in the case of 

 Phoxichilidium femoratum} The question of the circulation 

 has been touched upon by a number of observers, being most 

 thoroughly considered by Dohrn (1881), but as this author makes 

 no mention of earlier writers, it may be well to give here a brief 

 resume of the literature on the subject, together with a few ad- 

 ditional observations. 



Johnston (1837, pp. 374 and 379) appears to have been the 

 first to mention a circulation of the fluids in the pycnogonid, 

 his observations being made on the living "Oriihyia coccinea'^ 

 {= I^hoxichilidium femoratum). Johnston, however, apparently 

 mistook the branching intestine for blood vessels, for he says 

 (p. 374) : "The circulating system is probably reduced to a single 

 vessel which occupies the centre of the thoracic segments, and 

 sends a branch to each member or limb, in which the blood has 

 an irregular movement, but cannot be said properly to circulate." 

 On p. 379 he adds that "there is no heart." Milne-Edwards, in 

 his "Histoire naturelle des Crustaces" (1840, p. 531), dismisses 



^ Phoxichilidium femoratum is well known on our coast to the northward of Cape 

 Cod. 



