96 PERCY SLADEN TRUST EXPEDITION. 
of the various terms applied to different parts of the body by himself, by Meinert (1899), 
Sars (1891), Hoek (1881), Dohrn (1881), and Wilson (1880). All these authorities 
agree in calling the anterior region of the body that carries the eyes and the first four 
pairs of appendages a “ segment,” qualifying it variously by such terms as “first trunk,” 
“cephalic,” ‘ cephalothoracie,” or ‘‘ oculiferous.” Now, although it is undesirable to 
depart needlessly from established terminology, it is manifestly wrong to call a region 
that bears four pairs of limbs a “segment.” For this region I would suggest the 
term “ head,” having (1905) recently endeavoured to show that it corresponds with the 
primitive head-region of the Arthropoda. For the appendages of the head I use the 
terms “ cheliforus,” “ palp,” “oviger,” and “first leg.’ The term “oviger” is due to 
Cole, and by its use (in place of ‘ovigerous leg” or “false leg”) the cumbrous term 
‘ambulatory leg” is avoided. The three limb-bearing segments behind the head may 
naturally be called the second, third, and fourth ‘“ leg-bearing segments” respectively, 
the first leg-bearing segment forming part of the head. For the short terminal region 
of the body, the name ‘‘ abdomen” used by Hoek and Wilson is preferable to the ‘ caudal 
segment’ of Sars, Meinert, and Cole, since this region probably represents a number of 
segments fused together and contracted. The extreme degree of concentration in this 
region is shown hy the genus Rhopalorhynchus (see Pl. 18. fig. 27). 
This is hardly the place for any general discussion on the affinities of the Pyenogonida, 
but the writer has already offered support to the opinion of Lankester (1904) that they 
should be regarded as an isolated order of the class Arachnida. ‘The use of Pycnogonida 
as the ordinal name is inconvenient, as it may so easily be confused with the family- 
name Pyenogonidee. If it be replaced, its substitute must be the term Podosomata of 
Leach rather than the later, but more generally used, name Pantopoda. 
Family Pallenide. 
PALLENOPSIS, Wilson. 
1. Pallenopsis spinipes, sp.nov. (Plate 12. figs. 1-12.) 
Length 4 mm. (including proboscis and abdomen). 
Body stout, with the two hinder leg-bearing segments fused, and with the lateral 
processes close together (figs. 1, 2). Abdomen slender, elongate, with prominent paired 
dorsal spines (figs. 1,2). Proboscis less than half the length of body. Eye-eminence erect, 
acuminate at apex. Cheliforus with three segments, the scape consisting of one basal 
segment only, the second and third segments (“ hand” and “ finger”) feeble (figs. 3, 4). 
Oviger of male as long as head, thorax, and abdomen, the fourth and fifth segments of 
equal length, the sixth, seventh, and eighth together being as long as the fifth (fig. 5), 
Oviger of the female much shorter (fig. 6), with only eight segments (fig. 7). Leg with 
the thigh as long as the first tibial segment, the male’s cement-gland opening through a 
prominent tubular projection (figs. 1, 8, 9) on the flexor aspect of the limb. Second 
tibial segment as long as the first; propodus with three basal spines and two large 
accessory claws (fig. 11). Legs spinose, many of the prominent spines bearing numerous 
sharp denticles (fig. 10). 
Ne rll ere — Ps 
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