176 ON THE ANATOMY AND AFFINITIES OF 
monta” and “ Stylonurus,” which he considers to be new genera, but 
which are not as yet proved to be other than species of Eurypterus 
and Prerygotus. 
Mr. Salter communicated to the meeting of the British Associ- 
ation, in 1856, a paper “On the great Pterygotus (seraphim) of 
Scotland, and other Species,” containing his opinion as to the identity 
of the genera Avmantopterus! and Pterygotus, and some of the further 
anatomical facts which had at that time been elucidated. 
And, lastly, I stated the results of the same inquiries still more 
fully in my ‘“ Lectures on General Natural History,” published in the 
“ Medical Times and Gazette” for 1857. 
The evidence upon which the following attempt to give a 
connected account of the structure of Péexygotus is based, is both 
positive and negative. Numerous specimens testify to the existence 
of certain characteristically formed parts, and to the arrangement of 
these in a definite order in the body of the animal, so that its 
general configuration may be very confidently restored. On the 
other hand, the large number of fragments of many species of 
Pterygotus which have been inspected, without revealing anything 
new, leads me to entertain a strong impression that no structures of 
any very great importance remain to be discovered. 
With regard to the nature of the positive evidence, I may premise 
that of the fifteen distinguishable species of the genus, the remains 
of only five, viz., anglicus, acuntinatus, punctatus, perornatus, and 
bilobus have yielded facts of capital importance in a structural point 
of view; I shall, therefore, confine myself to these species, referring 
the reader to the systematic portion of this monograph for  in- 
formation respecting the rest, and indeed for all details of no. 
anatomical importance concerning even these. 
Of the species named, the only entire specimens yet discovered 
belong to P. dilobus, but the large size and comparatively perfect 
condition of the detached parts of P ang/icus, added to the fact that 
the genus was originally founded on this species, render it convenient 
to commence with a description of them. 
1. Lhe Carapace—In Lord Kinnaird’s collection there is a large 
flattened plate, figured in Plate III. [Plate 14] fig. 1, which appears 
to have possessed a trapezoidal form when perfect, but is at present 
very irregular (though by no means distorted), one of its angles and 
a considerable portion of the margin of the longest side having been 
1 The name Hemantoplerus could in no case have been retained, as it has been already 
used for a genus of lepidopterous insects. 
