Mr. J. W. Salter on new Fossil Crustaceans. 83 



the Eiirypterus tetragonophthalmus (Fischer) underlies Devonian 

 rocks ; and in the Russian Baltic island of Oesel, it has recently 

 been detected by M. Eichwald in a limestone which had been 

 referred by the author and his associates to the Ludlow rock. In 

 North America the Eurypterus occupies the same geological horizon 

 as in Russia and the British Isles ; and it is to be remembered 

 that large crustaceans of this group of Eurypteridaj have nowhere 

 been found in rocks of older date than the Upper Silurian. 



3. "Description of the Crustaceans from the Uppermost Silurian 

 rocks near Lesmahago." By John W. Salter, Esq., F.G.S. 



The large Crustacea referred to in the last paper were described 

 by Mr. Salter. They belong to the family Eurypteridse of Bur- 

 meister, and bear the closest relation to Eurypterus. They also 

 present many analogies with the Pterygotus, particularly in the 

 presence of a scale-like sculpturing on the body-rings, a character 

 now known to be present in Eurypterus, and probably common to 

 the whole family.. 



The}' are elongate crustaceans, with a comparatively short cara- 

 pace, bearing the large sessile eyes on the margin (and not on the 

 surface, as in Eurypterus), with ten or eleven body-rings unpro- 

 vided with any appendages, and with a caudal joint either pointed 

 or deeply bilobed. There are a pair of limbs adapted for swimming, 

 a pair of maxillae with serrated edges, and an anterior pair of long 

 appendages with dilated bases, in all probability antennae {Euryptei-us 

 has two pairs developed). From the strap -shaped or ligulate form 

 of the swimming, feet, the name Himantopterus is proposed in con- 

 trast with Eurypterus, which has these organs dilated. 



Five or six species were described ; all new. 



1 . H. acuminatus ; a foot long, with a mucronate caudal appendage. 



2. H. bilobus ; 7 inches long, the tail bifid. 



3. H. lanceolatus, a smaller species, with a simply pointed apex. 



4. H. maximus. The head only known ; it must have been 3 feet 

 long when perfect, and is the largest known. {Pterygotus may have 

 been about the same size.) 



5. H. } simulans. A large species, with very distinct sculpture. 



6. H. Banksii. A small species from the Tilestones of Kington, 

 Herefordshire ; 3 or 4 inches long. 



A note by Mr. Huxley, on the relations of these gigantic extinct 

 Crustacea, showed that their zoological position was neither among 

 the Phyllopods nor the Pcccilopods, nor intermediate between the 

 Copepods and Isopods, as had been supposed, but that their struc- 

 tural peculiarities were to be paralleled only among the Cumoid 

 Stomapods on the one hand, and the zoaform larvae of the Macrura 

 on the other. Drawings of a new genus of Cumoid Crustacea, Ca- 

 lyptoceros, illustrated this position ; and leaving out of considera- 

 tion the Isopoda, Pcecilopoda, and Trilobita, it was shown that the 

 Eurypteridse exhibited the most rudimentary and larval forms of any 

 known Crustacea. 



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