598 
PALAEONTOLOGY OF NEW-YORK. 
Peltura (Oleims) holopyga (n. s.). 
Entire form elongate subelliptical, having a length of about twice and a 
half the width. Head somewhat semielliptical; the posterior angles 
produced in long spines. Glabella strongly lobed, its length a little 
greater than its greatest breadth ; the whole breadth of the head, when 
entire, being about twice as great as the length. Hypostoma wider than 
long. 
Thorax with eleven articulations ; the middle lobe prominent, and about 
twice as wide as the lateral lobes; the articulations strong, rounded 
above, and each one marked in the centre by a node (or the base of a 
spine which has been broken off in the specimens examined ). Arti¬ 
culations of the lateral lobes short (the extremities of the upper ones 
broken off in the specimen); the lower ones bending abruptly down¬ 
wards and' terminating in spiniform processes, the last pair being 
\ 
prolonged much beyond the extremity of the pygidium. 
Pygidium longitudinally semielliptical; the middle lobe marked by three 
annulations, and a fourth obscure one above the terminal lobe : lateral 
lobes flat and plain, the exterior margin apparently free from ornament 
or inequality. 
The specimen from which the description and figure have been made is imperfect, 
in the absence of the cheeks with the posterior spines and frontal limb. These parts, 
with the hypostoma attached, lie upon the stone a little in advance and turned to 
one side of the head of the specimen, and have been drawn in their proper relations, 
but not attached to the head. That this portion of a trilobite belongs to the one 
figured, can scarcely admit of doubt; but in the absence of an entire head, which 
would warrant the restoration, I have given the figure as it occurs on the stone, 
with merely a change of the position of the two parts. It is not proved, from this 
specimen, that the third articulation from the head may not have extended beyond 
the others, as shown in the two preceding species. 
This species appears to belong to the Genus Peltura, taking the figures of Olenus 
( Peltura ) scarabceoides as the type of the genus*. Our specimen differs from that one 
* This species, the Entomostracites scarabceoides of Waiilenberg, 1821 ( scarabceorum vel aliorum 
vaginipennium animale vestigia : Bromel in Act. Litt. Upsal. 1729), lias apparently been drawn from 
