318 ARACHNIDRS. 



They are found among marine plants, sometimes under stones near 

 the beach, and occasionally also on the Cetacea. 



PYCNOGONUM, Brun., Mull., Fab. 



The chelicerae and palpi wanting ; length of the feet hardly greater 

 than that of the body, which is proportionably thicker and shorter 

 than in the following genera. They live on the Cetacea *. 



PHOXICHILUS, Lat. 



The palpi wanting, as in the Pycnogoni ; but the legs are very long, 

 and there are two chelicerae f . 



NYMPHON, Fab. 



The Nymphones resemble the Phoxichili in the narrow and oblong 

 form of their body, the length of their legs, and in the presence of 

 chelicerae ; but they have, besides, two palpi J. 



FAMILY III. 



HOLETRA. 



The trunk and abdomen are here united in one mass, under a com- 

 mon epidermis, or, at most, the thorax is divided by a strangulation, 

 and the abdomen, in some, merely c-xhibits an appearance of annuli, 

 formed by the plicae of the abdomen. 



The anterior extremity of their body frequently projects in the 

 form of a snout or rostrum : most of them have eight legs, and the 

 remainder six ||. 



This family consists of two tribes. In the first or the PHALANGITA, 

 Lat., we observe very apparent chelicerae which either project in 



* Mull. Zool. Dan., CXIX, 1012, the female. Found on our coast by MM. 

 Surirey and D'Orbigny. 



t Refer to this genus the Pycnogonum spinipes of Othon Fabricius, his variety of 

 the P. grossipes, without antennae ; the Phalangium aculeatum ; the spinosum, Montag., 

 Lin. Trans. ; the Nymphon femoratum of the Acts of the Soc. of Nat. Hist, of Copen- 

 hag., 1797 ; the Nymphon hirtum, Fab., which perhaps does not differ from the Phal. 

 spinipes and spinosum above quoted. 



J Pycnogonum grossipes, Oth. Fab. ; Mull., Zool. Dan., CXIX, 5 9, the female; 

 to compare with the Nymph, gracile and femoratum, Leach, Zool. Miscell., XIX, 1, 



2. His genus Ammothea A. carolinensis, Ib. differs from Nymphon in the che- 



licerse, which are much shorter than the month, the first segment or radical joint 

 being very small. The palpi consist of nine joints, while those of the Nymphoues 

 have but five. In this genus, as well as in Phoxichilus and Pycnogonum, the second 

 joint of the tarsi is very short. The tubercle on which the eyes are placed is some- 

 times situated on an elevation, which projects above the base of the anterior segment, 

 or the mouth. 



HOLETRA, Hermann. 



|| The Trombidium longipes, Hermann, Jun., Mem. Apter, pi. I, 8, is represented 

 with ten legs, the two first very long. He allows but eight in the text. 



