102 PERMIAN FOSSILS. 
Strophalosia Morrisiana occurs rarely at Tunstall Hill, Tynemouth Cliff (nm Breccia), 
Claxheugh, Dalton-le-Dale, Ryhope Field-House Farm; and rather commonly at 
Humbleton Quarry. A specimen, in the York Museum, of apparently the same 
species, was found at Nosterfield. I suspect it also occurs at’ Ferry Bridge (vide 
Phillips in ‘ Philosophical Magazine, N. S., vol. iv, p. 401, 1828). In Germany it 
occurs at Milbitz and Corbusen (Geinitz, ‘ Versteinerungen,’ p. 16). Unless some of 
the fossils assigned to its related form (Strophalosia Cancrinz) be the same, it would 
appear to be absent in the Permian deposits of Russia. 
STROPHALOSIA PARVA, King. Plate XII, fig. 33. 
Diagnosis—Form irregularly circular marginally. Large valve somewhat convex : 
umbone very small, and much impressed: spzzes numerous, long, and closely packed : 
area very small. Rarely exceeding a quarter of an inch in diameter. 
I have felt considerable difficulty in deciding whether this is the young of any 
of the former species, or a distinct one; but after a careful examination of a number 
of specimens, I have been led to adopt the latter conclusion. Strophalosia Morrisiana 
and 8. Goldfuss: are the only species to which it is likely to be referred; but. its 
umbone is much more impressed, and its spies are decidedly more numerous and 
more elevated, than in the first: with Strophalosia Goldfussi the present species agrees 
somewhat in the profusion and direction of its spines; but in the former the umbone, 
although very much impressed, is more prominent. 
Its habit of adhering to the inside of other shells (generally Productus horridus) 
has already been noticed. The umbone (vide Plate XII, fig. 33 a) is the part by 
which the shell was attached: the spines in this region were also thus subservient, as 
proved by their mode of spreading over the inside of the shell to which they adhered, 
and following its curvature: the remaining spines, those on the frontal slope of the 
valve, were free and straight ; they also struck off from the surface of the valve at a 
considerable angle, and extended considerably beyond its margin,—all of which 
characters are fully displayed on a specimen which I have lately procured, but at too 
late a period for its being figured in the present work. 
Strophalosia parva has only occurred to me in the shelly limestone of Humbleton 
Quarry.” 
1 T cannot conclude the Productide without noticing an observation of Dr. Thomson’s, leading to the 
belief that Mr. James Sowerby had recognised nearly all the species of this family herein described: “Mr. 
Sowerby considers that he is able to distinguish no fewer than casts of five species of Productus in the 
specimen which I brought from Humbleton Hill.” (Annals of Philosophy, vol. iv, p. 18, 1814.) 
