MARL-SLATE AND LOWER MAGNESIAN LIMESTONE. 185 



well as to those species that are found in the sub-formations 

 higher in the Series, notice will be taken of one or two localities 

 where fossils have been obtained from the Marl-slate, which 

 underlies the Lower Limestone. 



MAEL-SLATE. 



Cullercoats. — During the past year (1865) a remarkably fine 

 series of fish have been procured by Mr. Thomas Atthey, from 

 the outlying bit of Marl-slate in the bay at Cullercoats. The 

 position of this piece of Permian strata is of course on the north 

 or dip side of the 90 fathom dyke, to which it in fact owes its 

 preservation. It lies between tide marks, and is not easily 

 examined. I know of no other locality that has produced so good 

 a collection of these fossils, either in respect to the quantity of 

 species, or the quality of specimens, but this may in a great 

 measure be owing to it having been searched by one of the 

 best observers and manipulators in the North. Some of the 

 specimens are probably the most perfect of the species yet dis- 

 covered, and may ultimately assist in completing the descriptions 

 already published. 



LIST OF SPECIES. 



Pygoetertts mandibtjlaris, Agassiz. 



Two very fine examples of this species have been found by 

 Mr. Atthey. One is 26 inches in length, and of a slender and 

 elegant form : it shows the caudal, anal, dorsal, ventral, and 

 pectoral fins ; also the interspinous bones, those of the head and 

 the teeth. This specimen is remarkably well preserved, and 

 probably the most perfect individual of the species that exists. 

 The other is only 15 inches long, and of greater relative width 

 or height. 



Platysomus striattts, Agassiz. 



A single fine specimen, 9 inches long, and 4 inches high, with 

 the tubercular teeth well exposed. 



