BRITISH FOSSILS. 9 



ratus resembling the existing Limulus. The Pterygotus could 

 be classed with no living family, and was in aspect more like the 

 larvae than the adult forms, of any Crustacea with which we are 

 acquainted. This peculiarity, indeed, ran throughout the whole of 

 the Crustacea, (and there were several new forms he would notice 

 on another occasion,) which had hitherto been found in this 

 geological horizon, a horizon that would yet be found to be 

 marked peculiarly by its strange Crustacea. From the portions he 

 now exhibited to the section, the members eould perceive at a 

 glance that the restoration by Professor M'Coy was altogether 

 erroneous, and bore scarcely any resemblance to what the crea- 

 ture must have been when alive, and acting the part of a 

 scavenger along the muddy shores of the Old Red Sandstone seas. 

 The figures on the walls (Mr. Page here exhibited what he con- 

 ceived to be a near approach to a complete restoration) would 

 afford some idea of the general features of the animal, which he 

 had found of all sizes from ten or twelve inches up to full five or 

 six feet in length. Such was the Pterygotus, and looking at its 

 complex structure, as well as the similar structure of other Crus- 

 tacea of the period, there could be no doubt that no existing 

 classification of the order embraced them in its subdivisions. The 

 fact was, that the existing Crustacea were by no means well 

 worked out as a group, and the discovery of these strange fossil 

 forms rendered the study still less perfect." 



The comparative anatomist acquainted with the labours of Milne 

 Edwards, Dana, Bell, Baird, Schaeffer, Darwin, and a host of other 

 workers, will hardly be disposed to agree with the opinion expressed 

 in the commencement of Mr. Page's last paragraph, though doubt- 

 less a good deal remains to be done. In Mr. Page's reference of the 

 Pterygoti to a distinct group, he has, as we have seen, been antici- 

 pated, and his restoration of their structure is hardly more fortunate 

 than that of his predecessors. His " posterior cephalic or thoracic 

 shield " is the epistoma, and has a wholly different place from that 

 assigned to it ; like Agassiz and M'Coy he places the chelae 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 com- 

 municated 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 Himantopterus. 



Mr. Salter points out the differences between Himantopterus 



