46 



BEITISH FOSSILS. 



and pits over the greater part of their surface ; narrow smooth 

 facets being left along two sides to receive the overlapping edges of 

 other scales. 



A single longitudinal row of hexagonal scales occupies the middle 

 line of the back, and a less marked row of rhombic scales runs along 

 the ventral median line. The lateral scales, rhomboidal in form, 

 extend from the medio-dorsal to the medio-ventral series, forming 

 curved rows transverse to the axis of the body in general direction, 

 but presenting a marked concavity, or re-entering angle, forwards. 



With respect to the dentition of Glyptolwmus, I find a series of 

 minute pointed teeth along the outer margins of both upper and 

 lower jaws. Besides these there is a single large tooth upon each 

 side of the symphysis of the mandible, and at least one more of the 

 same kind, a little in front of the middle of the ramus (fig. lb, 

 Plate II.) In the upper jaw, the pterygopalatine apparatus is, fis 

 I have already pointed out, provided with several similar teeth. 



Glyi')tol(Emus is at present only known to occur in the Old Red 

 Sandstone of Dura Den. 



Explanation of Plates I. and II. 



Plate I. 



Fig. 1 . Side view of a specimen of GlyptoltEmus Kinnairdi, half the size of nature. 



This and the other figures of the plate are taken from specimens in the 



Museum of Practical Geology. 

 Fig. la. Head of the same, natural size. 

 Pig. 2. Ventral and anal fins of another specimen. 



Pig. 3. Ventral view of another specimen, half the natural size. Mus. Pract. Geol. 

 Pig. 4. Scales magnified. , 



Plate II. 



The figures give various views of a specimen of Glyptolcemus Kinnairdi in the Museum 

 of Practical Geology, and are all, except 3, 4, and 5, of the natural size. 

 Pig. 1. Dorsal view of the body. 

 Pig. la. Lateral view of the head. 

 Pig. lb. Pront view of the head. 

 Pig, Ic, Ventral view of the body. 



Pig, 2. Sandstone matrix into which the body fits, and which retains many of the dorsal 



scales and the pectoral fins. 

 Pigs. 3, 4, and 5. Scales from different parts of the body magnified. 



November I, 1861. 



T. H. Huxley. 



