H. Woodward—Eurypterus lanceolatus. 109 
for them to have occupied during life, and in which they never 
occur im any examples that I have seen of the closely allied 
Pterygoti from Lesmahagow, many of which have these parts 
well preserved in szti. 
A single antennule discovered by Mr. Slimon shows these 
appendages to have eight articulations: the broad basal joint is 
serrated along its inner margin, and evidently served the pur- 
pose of a manducatory organ. ‘The three succeeding pairs are 
serrated along their articulations ; but are not so spinose * as in 
the American species, or in those discovered by Dr. Scouler in 
the Burdie-house Limestone, and described and figured under 
the name of Hurypterus Scoulert by Dr. Hibbert in the ‘ Trans- 
actions of the Royal Society of Edinburgh’ (1836, vol. xiii. 
p- 281, pl. 12). The metastoma, or post-oral plate, is cordi- 
form and quite destitute of any median ridge or ornamentation. 
Its lateral margin slightly overlaps the interior margins of the 
broad basal joints of the swimming-feet, whose serrated palpi 
fulfil without doubt, in this as in all the other species of 
Eurypteride, the chief duty of mandibles. 
A slight groove or furrow surrounds the anterior and antero- 
lateral margins of the carapace, gradually thinning off and 
disappearing at the latero-posterior margins. In his ‘ Paleon- 
tology of New York’ (1859, vol. i. p. 397), Professor Hall 
gives the number of articulations in the swimming-feet of 
Eurypterus as ‘eight, with a terminal palette.’ He evidently 
considers the intercalated plate (seen in the figure) to form a 
part of the seventh segment; for he says, op. cit. p. 397, ‘ At the 
line s there is a soldered suture, connecting the fixed ramus 
of the chela with the penultimate joint. In some specimens the 
parts have been separated along this line.’ In the specimen 
from Lesmahagow I have been unable to discern more than 
seven articulations and a terminal palette. The third appears 
to be the absent joint; and Professor Hall says (p. 397): ¢ In 
indicating the number of joints, I have been governed by no 
theoretical views, but simply by the appearances of separation 
in the parts; and though the two extremities of the third joint, 
as marked, show no articulating processes, the limitation of the 
parts is distinct, and they may have been separated only by a 
thin extension of the chitine, and may not be properly articu- 
lating surfaces.’ Supposing then this third joint of Professor 
Hall to be absent, we shall agree exactly in the number of 
* A single antenna is seen in Mr. Wright’s specimen; it is more robust than the 
antennule, and the number of joints appears to be eight, but they cannot be clearly 
made out. A specimen in Mr. Slimon’s cabinet shows two of these simple palpi 
in sitté; but does not help us as to the number of the joints. 
