318 
ARACHNIDES. 
They are found among' marine plants, sometimes under stones near 
the beach, and occasionally also on the Cetacea. 
Pycnogonum, Brim., MiilL, 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, Lai. 
The palpi wanting, as in the Pycnogoni ; but the legs are very long, 
and there are trvo chelicerae •]•. 
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 Ijy a strangulation, 
and the abdomen, in some, merely exhibits an appearance of annuli, 
foi’ined 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 1|. 
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, 10 — 12, the female. Found on our coast by MM. 
Surirey and D’Orbigny. 
d- Refer to this genus the Pycnogonum spinipes of Othon Fabricius, his variety of 
the P. grossipes, without antennae ; the Phalangiumaculeatum ; 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 sjnnosum above quoted. 
X Pycnogonum grossipes, Oth. Fab. ; Miill., Zool. Dan., CXIX, 5 — 9, the female; 
to compare with the Nymph, gracile nnA femoratum, Leach, Zool. Miscell., XIX, 1, 
2. His genus Ammothea A. carolinensis, Ib. — differs from Nymphon in the che- 
licera;, which are much shorter than the mo- th, the first segment or radical joint 
being very small. The palpi consist of nine joints, while those of the Nymphones 
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. 
II 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. 
