1838 ON THE ANATOMY AND AFFINITIES OF 
three joints, and the distal margins of the outer of these joints 
in the anterior “palp” are produced into strong curved processes 
or sete. 
The part represented in Plate XIII. [Plate 24] fig. 4, appar- 
ently consists of these palpiform appendages detached from their 
basal joint. Four or five gradually tapering joints are here distin- 
guishable, and each is produced into sete along its distal edges, while 
the terminal articulation resembles a curved claw. 
The same kind of basal plate, apparently provided with similar 
appendages, is shown in another specimen (Plate XIII. [Plate 24] 
fig. 3), but the parts are here overlapped by the broken ectognath, 
and are so crushed and confused that I can arrive at no satisfactory 
conclusion regarding them. 
A valuable example of P. acuminatus from Lesmahago (Plate XV. 
{Plate 26] fig. 1), although greatly crushed, and at first sight very 
unpromising, yields a great deal of valuable information on patient 
investigation, and shows, among other things, that the organs under 
‘discussion belong to the mouth and to the endognathary series. In 
fact, in both halves of this specimen, the ectognath and the metastoma 
are very clearly traceable, and are evidently almost undisturbed. 
The palps of the ectognaths are displayed zz sztw on each side ; 
the cutting edges of these appendages are seen on each side of 
the middle line and are turned towards one another, while the large 
metastoma lies between them, overlapping their respective inner 
margins. Internally to their serrated edges, a series of articulated 
teeth (c’), like those connected with the free edge of the basal joint 
of the organ described above, can be seen upon each side, but the rest 
of the basal joint cannot be made out. 
On the left-hand side of the head, however, the remains of two 
palpiform bodies (c), evidently of the same nature as those described 
above, and provided with similar strong curved sete, are visible. On 
the right side is an impression of a similar character, but its minutiz 
cannot be satisfactorily deciphered. 
The facts I have detailed may be variously interpreted. Either 
the two palps belong to one basal joint, or there are two basal 
joints, each with a palp. In the former case there would be one 
endognath on each side, with a double palp; in the latter, two 
endognaths, each with a single palp. As the evidence stands at 
present, I see no means of arriving at a well-grounded opinion on 
this subject, and I prefer to abstain from conjecture. 
3. Plerygotus perornatus.—The opposite impressions of part of 
an example of this species are exhibited by two slabs, each of which 
