ASTEROLEPIDJE. 
217 
P. 655. Much crushed, imperfect specimen. Egerton Coll. 
P. 655 a. Small specimen, wanting head. Egerton Coll. 
P. 5053. Small specimen, in counterpart, scarcely crushed, wanting 
the head. ■ The half exhibiting the ventral plates from 
the visceral aspect is shown, of the natural size, in PI. VI. 
fig. 1. The various elements are indicated by the letter¬ 
ing, and some of the overlapping margins of the plates are 
well seen. Presented bg J. E. Lee , Esq., 1885. 
Pterichthys productus, Agassiz. 
[Plate V. fig. 9 ; Plate VI. fig. 2.] 
1844. Pterichthys productus and P. cancriformis, L. Agassiz, Poiss. 
Foss. vol. ii. pt. i. p. 302 (names only). 
1844. Pterichthys productus, L. Agassiz, Poiss. Foss. V. G. P. p. 16, 
pi. v. figs. 1-4. 
1844. Pterichthys cancriformis, L. Agassiz, ibid. p. 17, pi. i. figs. 4, 5, 
[British Museum.] 
1848. Pterichthys productus, Sir P. Egerton, Quart. Jo urn. Geol. Soc. 
vol. iv. p. 312. 
1855. Pterichthys cancriformis, F. M‘Coy, Brit. Palgeoz. Foss. p. 509. 
1855, Pterichthys productus, F. M‘Coy, ibid. p. 600. 
1880. Pterichthys , J. Laliusen, Verhandl. russ.-kais. mineral. Gesell. 2] 
vol. xv. pi. ii. fig. a. 
1888. Pterichthys productus, Ii. II. Traquair, Geol. Mag. [3] vol. v. 
p. 509. 
Type. Imperfect individuals, ventral aspect; British Museum 
and Forres Museum. 
Inferior surface of carapace narrowly ovate; tail about equal in 
length to the trunk. Pectoral appendages about two-thirds as long 
as the trunk, the distal segment considerably expanded. 
Form. Sf Loc. Lower Old Bed Sandstone : Nairnshire, Banffshire, 
Boss-shire, and Orkney. 
(i.) Lethen Bar. 
P. 534, P. 3212. One of the type specimens, in counterpart, figured 
by Agassiz, op. cit. pi. v. fig. 1. The fossil exhibits the 
ventral aspect of the head and trunk and right pectoral 
appendage, much broken, and is re-figured in PI. V. fig. 9, 
with explanatory lettering. Egerton <Sf Enniskillen Colls. 
P. 547. Counterpart of one of the type specimens figured by Agassiz, 
op. cit. pi. v. fig. 2. Egerton Coll. 
