THE GENUS PTERYGOTUS 175 
assigned to it; like Agassiz and M‘Coy he places the chelz at the 
end of the ectognathary palps, and considers them to terminate 
thoracic appendages. 
Mr. Page’s paper was read before the British Association at its 
meeting in 1855. In November of the same year Mr. Salter communi- 
cated a paper to the Geological Society “On some new Crustacea 
from the Uppermost Silurian Rocks,” to which I added a note on the 
structure and affinities of Hemantopterus. 
Mr. Salter points out the differences between A7ziantopterus 
and Eurypterus, and establishes six species of the former genus, 
whose structure and affinities are discussed in my own note. Subse- 
quent investigation has confirmed the views therein taken of the 
carapace, its eyes, the chelate antenna, the swimming feet, the 
general structure of the body, and the absence of abdominal or 
thoracic appendages ; nor has it, as yet, been absolutely proved that 
there were more than three pairs of cephalic appendages; but the 
basal joints of the ectognaths were mistaken for mandibles, and 
their connexion with the long palp-like swimming foot was not 
observed. Neither the epistoma nor the metastoma (the latter 
is figured in the restoration as a “scale-like appendage”) were 
determined. In inquiring into the affinities of Hzsmantopterus, I 
compared it successively with the Phyllopoda, the Pectlopoda, the 
Copepoda, and the grounds on which I objected to refer it to either 
of these orders seem to me still, substantially, to hold good. I then 
proceeded to compare it with the Cumoid Crustacea, with certain 
Stomapoda, and with the embryonic forms of the higher Crustacea, 
and I concluded by expressing the opinion, that “the nearest 
approach to Azmantopterus which could be constructed out of the 
elements afforded by existing Crustacea, would be produced by 
superinducing upon the general form of a Cumoid crustacean, such 
a modification of the appendages as we find among the Zoceiform 
Macruran larve.”! 
In his “ Advanced Text-Book of Geology,” p. 135 (1856), Mr. 
Page gives a figure of one of the specimens on which W7mantopterus 
was based, and provisionally admits that genus, adopting the 
“Cumoid” affinities which I had suggested. He considers that 
those paleozoic Crustacea and their allies exhibit, “as it were, an 
interfusion of phyllopod, pzcilopod, and decapod—of brachyurous, 
macrourous, and xiphosurous forms,” and figures and names “ Si- 
1 Mr. Salter has misunderstood me, when he says at the end of his memoir (Z¢.) that I 
consider Himantoplerus to be ‘one of the Slomapoda.” On the contrary, I have always 
been prepared to admit the ordinal distinctness of the Zuryplerida. 
