from Queen's County, Ireland. Ill 



The spine or telson which is attached to this portion exhibits a 

 central longitudinal ridge, having a membranous expansion on 

 each side similar to that noticed by Parkinson as occurring in 

 the species described by Martin, and which I have referred to 

 B. bellulus, Konig. 



The following are the measurements of fig. 1 A : — 



[The line is considered as being the twelfth of an inch.] 



Total length from anterior margin of 



cephalic shield to point of telson. . 1 inch 1 line, or 27 mill. 

 Breadth at widest part of spines . . 7 lines or 15 „ 



„ of cephalic shield 5 „ or 10 „ 



Length of telson 10 „ or 20 „ 



Measurements of fig. IB: — 



Length of, from anterior margin of 



cephalic shield to end of tail .... 5 lines or 10 mill. 

 Length from anterior to posterior 



margin of cephalic shield 2\ „ 5 „ 



Breadth of cephalic shield 6| „ 13 „ 



Length of body and tail 1\ „ 5 „ 



Breadth of body at cephalic shield . . 4 ,, 8 „ 



Locality. From Coal-shale, Bilboa Colliery, Queen's County. 



Belinurus arcuatus, n. sp. PI. V. fig. 2 A-C. 

 Diagnosis. — B. latus ; limbo scuti cephalici orbiculari, angulis longi- 

 spinosis ; glabella spinis duabus brevioribus munita ; thorace quiu- 

 que articulis brevispiuosis ; pleuris usque ad terminos sulcatis ; 

 tripartita cauda, cui spina longa coaptatur. 



Description. — General form broadly ovate, acuminate poste- 

 riorly ; axis convex. Cephalic shield semicircular, slightly ele- 

 vated, declining towards the circumference, and surrounded by 

 a narrow flattened margin ; the central portion or glabella having 

 three ridges extending to about two-thirds the breadth of the 

 shield, rounded at their anterior extremity, and forming a double 

 arch, the central portion being broadest at its posterior extremity, 

 the two outermost ridges curving at about half their length to- 

 wards the very slightly raised semicircular eyes, and continuing 

 beyond the posterior extremity of the shield in two sharp straight 

 spines, which project over the body about one-tenth of an inch; 

 the posterior angles of the cephalic shield are produced into 

 long spines, as in the preceding species, three-tenths of an 

 inch in length, slightly curved, and spreading out on either 

 side from the body. Thoracic rings five, which, as in the pre- 

 ceding species, decrease in breadth towards the posterior extre- 

 mity ; the lateral lobes, extending in a straight line, terminate 

 in a short spine, and have an angular furrow, which proceeds to 

 the end, curving at the same angle to the point of each spine. 



