2 
E. B. Wilson — Pycnoyonida of New England. 
in some species with an apparatus somewhat resembling the three 
denticulated jaws of a leech. The homologies of the rostrum are 
still uncertain ; by Huxley it is regarded as representing the united 
cheliceroe and pedipalpi, like that of the Acarina. 
In many genera a pair of palpi are present, attached below the 
bases of the antennae at the sides of the rostrum ; they are composed 
of five to nine joints, and sometimes are furnished with sense organs 
in the form of plumose hairs. 
The third pair of appendages, which are wanting in the males of 
certain genera, have been termed “ ovigerous legs,” from their office 
of bearing the egg-masses in the female, it having been supposed, 
formerly, that they were never present in the male. This term is, how- 
ever, inappropriate, when applied to the male appendages, and it 
appears preferable to term them accessory leys , as certain writers have 
done, at least until their homologies are better understood. 
The legs are eight in number, and are, in many forms, remarkable 
for their great length ; they are composed of nine joints, the termi- 
nal of which is claw-like, and, in many cases, forms with the preced- 
ing joint or propodus a subcheliform “ hand.” In certain genera it 
is armed with two movable claws articulated to its upper side near 
the base. 
The genital openings are eight in number in all the forms which I 
have examined. They are on the lower side of the second joint of the 
leg, near the distal extremity. 
The Pycnogonida, as a whole, have not been very carefully 
studied by systematic zoologists. To the researches of I)ohrn, 
Quatrefages, Zenker and others, we owe a tolerably full knowledge of 
their anatomy and, in some cases, of their embryology. The system- 
atic work has, with few exceptions, been unsatisfactory, owing to 
the paucity of generic and specific characters, the great variation 
in some of the species, and the difficulty of obtaining large series of 
specimens. The North American forms have hitherto received little 
attention. Leach described an Ammothea from Carolina ; and Stimp- 
son another species of this genus from Puget Sound. In 1853 the 
latter enumerated five species in his “Invertebrata of Grand Manan,” 
four of which were described as new. These are the only detailed 
descriptions hitherto published, although three or four species are 
mentioned, accompanied in some cases by brief notes, in papers by 
Professors Verrill, Smith, Packard and others. The u Pasithoe 1 ' 1 
described by Dr. Gould (Proc. Bost. Soc. Nat. Hist., vol. i, p. 92 ) is 
indeterminable. 
