258 CATALOGUE OF THE FOSSILS OF THE PERMIAN SYSTEM 
dyles of the lower valve: surface of both valves covered 
with close rows of small spines, which are rather regularly 
arranged. ; 
In Magnesian-limestone ; not uncommon. Humbleton, Tun- 
stall, Dalton-le-Dale. 
This is generally found with the preceding species. It may 
easily be distinguished from them by its neat and regular form, 
the smallness of the beak, and the regular disposition of the 
spines. 
In Prof. Sedgwick’s list two species of Productus, P. antiquata 
and P. spinosa, which are peculiar to the Mountain-limestone, are 
stated to have been found in the Magnesian-limestone at Mid- 
deridge and Humbleton. It is almost unnecessary to say we 
have not found either of these species which must have been in- 
troduced by mistake. 
ARTICULATA. 
ANNELIDA. 
34, SERPULA, Linneus. 
. §. MINUTISSIMA, 2. s. 
Serpula small, vermicular, nearly cylindrical, smooth. 
In Magnesian-limestone ; not uncommon. Tunstall, Humble- 
ton, Dalton-le-Dale. 
This small species of Serpula is generally attached to the outer 
surface of Terebratule, and the inner surface of valves of Pro- 
ductus and the chambers of a Nautilus. It is rather elongated 
and vermiform, and requires to be examined with a powerful lens. 
35. SPIRORBIS, Lamarck. 
. 8. atoBosus, I/‘Coy. 
Spirorbis globosus, M‘Coy, Carb. Foss. Ireland, p. 169, pl. 4, 
f. 10% 
In Magnesian-limestone ; rare. Humbleton. 
