DESCRIPTION OF THE SPECIES OF PTERYGOTUS 259 
A ppendages. 
-lntenne.—Of these great pincer-like organs only two chelz have 
been found, one three inches and a half long, but these are quite 
different in proportion from that of P. anglicus. The shaft is. much 
longer and slenderer, being quite eight times as long as wide, and 
not much thicker at the origin than near the tip. The teeth are 
much shorter, the central one is as long as the diameter of the chela 
itself, and placed beyond the middle; two other primaries nearly 
equal in size and a secondary tooth are outside it, while only minute 
teeth with a single primary near the hinge occur on the proximal 
half’ As many as twenty of these small conical teeth may be 
counted in the inner half, and eleven or twelve on the outer. The 
primaries are broad-conical (not ovate), striated and directed back- 
wards, and are not crowded at their bases by the smaller teeth 
which vary much in size, but are all of them more or less conical 
in shape like the larger ones. The terminal mucro is lost in both 
the specimens; a few tubercles occur on the shaft near the end, 
fig. 2 a. 
Endognaths and Palpi, figs. 5-8, and Plate XIII. [Plate 24] 
figs. g-11.—There are several specimens and they present some 
strong characters for the species. Plate XIII. [Plate 24] fig. 9, 
and Plate XI. [Plate 22] figs. 7 and 8, show portions of the palpi, 
and fig. 5 an endognath with its entire palp attached, and in the 
proper position in respect of the great swimming foot ¢c From this 
specimen it would appear that the remarkable spines of the palpus 
were directed forward. Figs. 8,9, show the great size these appendages 
obtained. 
The teeth of the maxillary piece (fig. 6 a a*) are small, short, and 
obliquely conical, not curved, and as in some other species striate ; 
there are about seven distinct, and six smaller ones, which last are 
either connected by a horny plate (as in P. anglicus), Plate VII. 
[Plate 18] fig. 5 6), or are confused with sete; the state of preser- 
vation does not permit us to decide which. The margin near the 
teeth is punctate, indicating the presence of hairs or sete. In some 
specimens the teeth are narrower and sharper. 
[Fig. 10, though found in the same bed, must evidently belong to 
a distinct species, and has been already referred to P. arcuatus. 
Fig. 11 is probably a second pair of jaws (endognaths), as already 
indicated in other species. ] 
Palpi—The great palpi (of which fig. 6 only shows the base at 
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