ASXEB0LEF1DJE. 
213 
P. 5599. Remains of a large trunk, with the right pectoral appen¬ 
dage, ventral aspect. Purchased, 1889. 
(ii.) Lethen Bar (typical P. latus). 
P. 533. One of the type specimens of P. latus, figured by Agassiz, 
op. cit. pi. iii. fig. 4. As remarked by Egerton, the fossil 
exhibits the ventral aspect, and most of the bone- 
substance is removed. Egerton Coll . 
28857. Crushed individual, dorsal aspect. The parts of the head 
are mostly obscured, but the mental plates are distinguish¬ 
able, and the pineal or “ os dubium,” with its median pit, 
is well shown. The anterior median dorsal plate is 
almost destroyed, but the smaller second dorsal is more 
complete; and immediately below and behind the latter 
occur the hinder extremities of the posterior ventro- 
laterals. Nothing worthy of note is presented by the tail; 
but in the left pectoral appendage, the transversely 
striated ginglymus upon which the distal segment moves 
is distinct. Purchased, 1854. 
49187. Trunk with head and fragments of the appendages and tail, 
ventral aspect, preserved in counterpart. The head is 
completely severed from the trunk, and the roof is shown 
from beneath, of the natural size, in PI. V. fig. 2. In 
addition to some of the elements ordinarily observed, and 
marked with letters in the figure, the pineal plate (p.) is 
well seen, with its central pit, and also one of the orbital 
plates (o.); moreover, a small process is observed to 
extend from the middle of the anterior margin of the 
postmedian plate (pt. m.). One of the extra-lateral plates 
is detached; and the plates of the appendages are 
scattered and broken. Purchased, 1878. 
49191. Head, trunk, limbs, and scattered remains of the tail, 
ventral aspect, preserved in counterpart. The posterior 
ventro-lateral plates exhibit denticulations on the hinder 
margin. Purchased, 1878. 
50109. Nearly complete individual, dorsal aspect, much crushed, and 
preserved in counterpart. The specimen is shown of the 
natural size in PL V. fig. 3. In the head the most 
important feature displayed is the pair of mental plates 
( mn .); they are somewhat displaced forwards, and their 
superior (or visceral) aspect is distinctly concave. The 
