DESCRIPTION OF THE SPECIES OF PTERYGOTUS 215 
of the epistoma, shaped as usual, and behind are two radiated mus- 
cular impressions (4) placed low down on the carapace, and towards 
the median line, which impressions are probably the attachments of 
the great swimming feet. 
We have only space to figure one of the seven body segments : 
the anterior six are probably thoracic, the last of these having a 
large projecting hinder angle which overlaps the base of the seventh 
(or first abdominal) segment. All the segments are conspicuously 
broader in proportion than in A. perornatus, the second, third, fourth, 
fifth, instead of nearly five times as wide as long, being not above 
three and a half times, and this difference is remarkable in the front 
segment (c), which in 1. perornatus is very transverse, seven times as 
broad as long, but in this is only four times and three-quarters as wide. 
It has very distinct anterior lobes, like those of the second segment. 
The sculpture of the rings differs from that of P. perornatus, in 
having the plica narrower and longer, the angular ones being less 
than go°,and even on the anterior margin they are not less than 
semicircular. 
Each segment except the first is crossed by a very distinct im- 
pressed line, which bisects the anterior sculptured half, and is placed 
in the second segment at the anterior third (in the first segment it is 
absent), the rest have it very near the anterior margin. 
The seventh segment is two and a half times as broad as long, and 
has square, not produced posterior angles. 
Locality—Lesmahago. Mus. Pract. Geology. (Collected by 
Mr. R. Slimon.) 
PLatTe NII. [PLATE 23] Fics. 22-46. 
Preryvcotus BANKSII. 
P. parvulus, 4-5 uncialis, capite convexo, semiovall, vel parabolico, ad 
frontem subangulato, oculis brevibus gibbis, ad dimidium capitis - annulis trunct 
omnibus transversis, caudd expansé truncata biloba. 
Synonym. Himantopterus Banksti, SALTER, Quart. Journ. Geol. Soc. 
vol. vii. p. 32, also p. 99, and pl. 2, fig. 5 [fig. 6, is the caudal joint of an 
Eurypterus},  Siluria, 2nd ed. p. 266, foss. 66, fig. 1. 
Named in honour of Richard Banks, Esq., of Kington, Hereford- 
shire, who has made rich collections of the Pterygott of that locality, 
and has generously relinquished the publication of his materials in 
our favour. He has also presented to the Museum all his accurately 
coloured drawings and notes. 
