Dv Hibbert on the Limestone of Kirkton. 



281 



hands Dr Harlan's account of the Eurypterus of North America, to which the 

 Kirkton specimens were readily referred 



The Eurypterus is assigned by Dr Harlan to the class Crustacea; and to the 

 order of Branchiopoda. His description of the genus Eurypterus is as follows : — 



Character of the Genus. — " Caput a thorace non distinctum : os ignotum : oculi 

 duo, sessiles, distantes, lunati : abdomen elongatum, posticam versus extremitatem 

 sensim gracilius, segmentis transversis subimbricatis divisum. Pedes octo ; duo 

 utrinque antici branchiferi, duo utrinque postici maximi, omnes lamellosi. 11 



Dr Harlan's specimens were obtained from a " transition calciferous sand rock" 1 

 of Westmoreland ill the Oneida county of New York. He has described two fossil 

 species, the Eurypterus lacustris and the E. Remipes. (See Plate XII. fig. 6. and 7.) 

 The head of the Eurypterus of Kirkton (see Plate XII. fig. 3.), which differs in 

 many respects from the American specimens, exhibits a physiognomy so human like, 

 that the quarrymen attributed it to some degenerate offspring of Adam. For this 

 reason, as well as in reference to the sort of examination which it seemed to invite, 

 the animal might have been stiled the Eurypterus phrenologicus. 



A more suitable specific title is, however, suggested. In honour of the naturalist 

 who has described in a satisfactory manner the only fragment, namely, the head and 

 a small portion of the abdomen, which came under his observation, I propose, to 

 name the Eurypterus found at Kirkton, the Eurypterus Scouleri. 



I consider the Eurypterus Scouleri to be distinguished from other species, by the 

 prolonged eminences intervening between the eyes, which at their apex form an angle 

 wherein appears a central tubercle ; — also by the small acutely angular protube- 

 rances, like spines, which are diffused over the surface of the head beneath the eyes. 

 The character of the feet cannot be given, as no vestiges of them, except very slight 

 ones, have turned up *. Perhaps, a last distinction is the greater size of the E. 

 Scouleri, which may be learned from the following table of comparison : 



EURYPTERUS LACUSTRIS. EURYPTERUS ReMIPES. 



Eurypterus Scouleri. 



Length of the head, 1 \ inch. 



Breadth of the head, 2| ... 



Distance between the eyes, 1 

 Breadth of the body, 2| ... 



Total length, . 5 





Larger Specimen. 



Smaller Specimen. 



1 inch. 



6 inches. 



5 iiiches. 



n ... 



8 ... 



64 ... 



3 



8 "* 



li ... 



ll'o -• 



1| ... 



8 ... 



5 



3f ... 



17? ... 



131? ... 



The Geological Relations of the Kirkton Limestone. — Above this deposit, we find 

 beds of very loose friable shale with ironstone bands, some of which are alternated 

 with its upper strata. These shale beds, composed of pure argillaceous matter, ap- 

 pear to have undergone few or no alterations from the action of heat. 



* In concluding this account of the Eurypterus, I beg to express my best thanks to Dr Simpson 

 of Bathgate, for giving me the opportunity of describing the specimens in his possession, as well as to 

 Mr Smith of Jordanhill, for the loan of the specimen in the Andersonian Museum of Glasgow. 



VOL. XIII. PART I. N II 



