1870. ] WOODWARD—PALPUS OF ASAPHUS. 487 
I was at once attracted by a speci- 
men of Asaphus, from the Black Trenton Fig. 1.—Buccal organs 
Limestone (Lower Silurian), which has of Asaphus platyce- 
bcen much eroded on its upper surface, phalus. 
leaving the hypostoma, and what appear 
tobe the appendages belonging to the first, 
second, and third somites, exposed to 
view, united along the median line by 
a longitudinal ridge. The pseudo-ap- 
pendages, however, have no evidence of 
any articulations. But what appears to 
me to be of the highest importance, as 
a piece of additional information afforded 7 hynostoma; p, palpus; | 
by the Museum specimen, is the dis- m, maxilla? 
covery of what I believe to be the jownted 
palpus of one of the maxille (Fig. 1), which has left its impres- 
sion upon the si 7 just, in fact, in that position 
which it must have occupied in life, judging by other Crustaceans 
which are furnished with an hypostoma, as Apus, Serolis, &e. 
The palpus is 9 lines in length ; the basal joint measures 3 lines, 
and is 2 lines broad, and somewhat triangular in form, 
There appear to be about seven articulations in the palpus itself, 
above the basal joint, marked by swellings upon its tubular stem, 
which is 1 line in diameter. 
There can be no reason to doubt that the Trilobita possessed an- 
tennules, antenne, mandibles, maxille, and maxillipeds, as we find 
the same organs preserved in Crustacea of equal antiquity (¢.g. Slimo- 
nia acuminata and Eurypterus remipes, both Upper Silurian forms). 
With regard to the “ Panderian organs” mentioned by Mr. Bil- 
lings, [ venture to suggest that the small circular impressions, seen 
upon the pleure of many Trilobites are only the fulcral points 
upon which the plewre move, and correspond to the ball-and- 
socket joints which mark the limbs and segments of all the higher 
Crustacea. 
We know of no Crustaceans having two pairs of appendages to 
each segment; but it is characteristic of Crustacea to have their 
appendages bifid, giving rise to an endopodite and an exopodite ; but 
these are always given off from a common base. 
Having regard to the characters presented by the Trilobita as a 
group, we should be inclined to place them near to, if not actually 
in, the Isopoda Normalia. 
In all this group, the branchis are abdominal, being placed under 
the broad and well-developed pygidium, which is not equivalent to 
the telson of the higher Crustacea, but is composed of several seg- 
ments soldered together, in fact, representing the true abdomen. It 
is here, then, we should expect to place the branchiz in the Trilo- 
bites, and not upon the epimera of the body-segments. 
If any objection should be urged against the organs observed in 
the specimen in the British Museum being really legs, I would sug- 
gest that they may be considered good evidence of the presence of 
