ON POSSIL CRUSTACEA. 323 



living species of Julus or Centipede. This is the second species of Myriopod 

 occurring in the Coal-field of Illinois, U.S., which has since also heen obtained 

 in England. 



Of the Merostomata only the suborder Xiphosura remains to be mono- 

 graphed, a task which I hope to complete during the present year. 



At the beginning of this year I was requested by Robt. Etheridge, .Jun., 

 Esq., F.G.S. (of the Geological Survey of Scotland), to examine some speci- 

 mens of Ceratiocaris from Lesmahagow, Lanarkshire. Among them was 

 one to which he specially drew my attention, as it presented the novel appear- 

 ance of appendages on the underside of the caudal series of segments. These 

 consist of giU-like plates depending freely from each segment. They are no 

 doubt analogous to those seen in Nehalia, which are supplementary abdominal 

 giU-feet. The discovery of these organs by Mr. Etheridge, which occur also 

 in several other specimens, does not in any way alter the position of Ceratio- 

 caris, but renders our knowledge of it more complete. 



Since Mr. Salter's paper " On Peltocaris, a new genus of Silurian Crus- 

 tacea," was published in 1863 (Quart. Journ. Geol. Soc. vol. xix. p. 87), I 

 announced a second genus, Discinocaris, in 1866 (see Quart. Journ. Geol. 

 Soc. vol. xxii. p. 503), also from the Llandeilo flags of Dumfriesshire. 

 Mr. Charles Lapworth, Mr. J. Wilson, Mr. Robert Michie, and others have 

 added several fine examples of this type of Phyllopodous Crustacea. The 

 largest of these is a portion of a carapace from Dobb's Linn, Moffat, Dum- 

 friesshire, and appears to agree best with Discinocaris ; but instead of being 

 a carapace the size of a threepenny piece, like Discinocaris Browniana, de- 

 scribed by me in 1866, this specimen, with its characteristic markings, gives 

 evidence of an individual 7 inches in diameter. Another specimen of this 

 same gigantic Phyllopod was obtained from Moffat by Robert Etheridge, jun., 

 Esq., F.G.S. , of the Geological Survey of Scotland. 



An entire carapace (of which three examples have been obtained), from the 

 Riccarton Beds, Yads Lynn, near Hawick, makes us acqiiainted with a new 

 genus, for which the name AjitycJiopsis is proposed. 



It measures 1| in. in length and 1| in. across. 



The nuchal suture is straight (not semicircular, as in Peltocaris), and it has 

 a well-marked dorsal suture, which again separates it from Discinocaris, in 

 which the dorsal suture is absent. 



I name this species Aptychopsis Wilsoni, after its discoverer. 



Another and more oval-formed but equally perfect carapace of a smaller 

 species, from the Moffat Anthracitic Shales, measuring 8 lines long by 7 lines 

 broad (having the triangular cephalic plate in situ), 1 have named AptycJiopsis 

 Lapivortlii, after Mr. Lapworth, who has devoted so many years to the inves- 

 tigation of the geology of Galashiels and the suiTounding district. 



A third species, very distinct from the foregoing two, obtained from the 

 Buckholm Beds (which is finely striated concentrically, and is 7 lines in dia- 

 meter), I have named ApitycJiopsis glahra. 



There are several other examples from this rich locality, including speci- 

 mens of Peltocaris aptyclioides, species of Dithyrocaris, Ceratiocaris, and 

 portions of the scale-marked integument of Pterygotus. 



I have lately received from Mr. Thomas Birtwell, of Padiham, Lancashire, 

 two specimens of a new Limuloid crustacean, in which all the thoracico- 

 abdominal segments are welded together into one piece, as in the modern 

 Limulvs, but without any trace of segmentation along the margin. 



The head-shield is also smooth, the compound eyes are small, but the larval 

 ocelli are very distinctly seen, and are almost as large as in the modern king 



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