908 THE VOYAGE OF H.M.S. CHALLENGER. 



behind them near together stand the three pairs of siagnopoda. These are all distinctly 

 visible in Dr. von Willemoes Suhm's mounted specimens, but finding in the collection one 

 preserved in spirits, that was taken in the Pacific near Fiji, I took advantage of the 

 circumstance to dissect out separately each oral member, and have figured them in the 

 plate (d, e,f, g). 



The mandibles (fig. Id) are simple, having an apophysis, but neither molar process 

 nor synaphipod ; the psalistoma is sharp-pointed and serrate. 



The first pair of siagnopoda (fig. le) is three-jointed ; the first two joints are broad 

 and foliaceous, and tipped with hairs on the inner margin ; the third is cylindrical, short, 

 and tipped with three or four hairs. Milne-Edwards says that the first pair is nearly 

 rudimentary and appears to consist of a small horny scale bordered with cilia. It 

 appears to me, on looking at the figures given by Milne-Edwards, that in his dissection 

 he has broken the appendage in two, and that his figures 6 and 7 put together will, 

 when combined, correspond with my figure (fig. le), which agrees with the representation 

 of the same appendage given by Anton Dohrn. 1 



The second pair of siagnopoda (fig. If) is three-jointed ; the central joint is bilobed, 

 and each is fringed with a cilium on the inner surface ; on the outer side is a broad, oval, 

 foliaceous plate that is fringed with hairs radiating centrifugally round the margin, and 

 is the homotype of the mastigobranchial plate of the higher groups of Macrura. This 

 corresponds with Milne-Edwards' third pair, and with the second maxillae in Anton 

 Dohrn's description. Claus 2 figures this appendage, representing the three internal 

 lobes much as they are given in my figure (fig. If), but he represents the outer folia- 

 ceous plate as being comparatively small and sparsely fringed with distant cilia ; it 

 should be remembered, however, that Claus drew his figure from an older specimen, 

 since he represents it with a seventh pair of pereionic appendages in a rudimentary 

 form. 



The third pan of siagnopoda (fig. lg) consists on the inner side of a four-jointed 

 appendage, of which the first or basal joint is broad, foliaceous, and fringed with hairs ; 

 the second, third, and fourth joints are narrow, cylindrical, and distally carry a single 

 hair on the inner margin ; at the base of the first joint on the outer side is a long and 

 slender biarticulate rod, furnished with cilia at the distal extremity ; at the base of this 

 rod there is a large ovate plate, the margin of which is fringed with distant cilia, and 

 near its base stands also a short membranous plate. The inner four-jointed branch I 

 believe to be the representative of as many joints of the typical leg, the outer rod 

 being the basecphysis, while the two foliaceous plates represent the mastigobranchia 

 and the rudiment of a branchial appendage in its saccular form. Milne-Edwards' figure 

 corresponds with mine in part only, omitting the two outer plates, which also correspond 



1 Untersuchungen fiber Bau unci Entwicklung der Arthropoclen, taf. xv. fig. 3, Leipzig, 1870. 



2 Crustaoeen-Systems, p. 48, taf. viii. fig. 9, 1876. 



