356 PROFESSOR E, RAY LANKESTER. 
assign the two pieces of the maxilla to one appendage—a 
single maxilla—but causes some difficulty in arriving at a 
conclusion as to what he means by denoting the maxillipede 
(rudimentary foot of Zaddach and Grube) as the “ second 
maxilla,” without any explanation as to the difference be- 
tween fis second maxilla and Zaddach’s. Huxley agrees 
with Claus in his statement, and characterises the second 
maxilla (my maxillipede) as foliaceous and almost rudi- 
mentary. 
Mandibles.—These are figured in Pl. XX, figs. 3, 3a, 
They appear to consist (according to Claus’s observations 
on their development) of the basal portion of the corm of 
the larval appendage, which had at one time a form similar 
to that of the second przoral pair of appendages (woodcut 
fig. ], XVIII). 
Mazille.—The maxille (right and left) consist each of two 
plate-like pieces fitted closely together, one behind the other. 
The piece furthest from the mouth (which was described by 
Zaddach as the second maxilla and by Gerstaecker, through 
an oversight, as the first maxilla) seems to correspond to 
the gnathobase or proximal endite (en!) of a thoracic foot. 
It is provided with numerous stout sete (Pl. XX, fig. 5). The 
piece nearer the mouth (Zaddach’s first maxilla, Gerstaecker’s 
second) is in the form of a half-arch of chitinous substance, 
with a broad surface for the attachment of the other piece. 
It is provided with very numerous delicate setz, which are 
arranged in the manner shown in the figures (Pl. XX, fig. 4), 
showing the aboral surface, and fig. 4a, the adoral surface. 
The exact relation of the arch of the maxilla (as we may 
term the last described piece) to the gnathobase is not quite 
clear from the account given by Claus of the development, 
but it is quite certain that it is only a part of the same 
appendage as the latter. 
Mazillipedes.—These appendages are of a very remarkable 
character. They have been universally recognised as rudi- 
mentary, not only on account of their small size (that drawn 
in Pl. XX, fig. 6, is on the same scale as that adopted for 
all the appendages), but also from the fact that they do not 
act as jaws on account of the wide separation of the right 
appendage from the left—whilst at the same time they are 
not fitted to be of much value as locomotor organs. They 
have not hitherto been correctly figured, the drawings of 
Zaddach and Grube being on a very small scale, whilst the 
drawing of Gerstaecker is out of all proportion in its ex- 
aggeration of the size relatively to that of other appendages, 
whilst the shape is incorrectly given. 
