264 Prof. W. King's Notes on Permian Fossils. 



of a Strophalosia {?) Morrisiana from Possneck. M'Coy con- 

 siders it to be the young of Strophalosia Goldfussi^ ; but its 

 hinge-line always appeared to me to be too wide to agree with 

 the " attenuated posterior end " of the latter : some other dif- 

 ferences, which I formerly pointed out, appear to separate both 

 forms from each other. 



Strophalosia Morrisiana-y, King. 



In my Monograph it is stated that " two varieties of Stro- 

 phalosia Morrisiana occur in the Permian rocks of Durham. One 

 has the large valve slightly convex, with a very small urabone, 

 and appears to be confined to Tuustall Hill : in the other, which 

 is rather common at Humbleton Quarry, the corresponding valve 

 is more rounded and the umbone more prominent : possibly they 

 are specifically distinct ; and it is this idea which causes me to 

 be particular in stating that the Tunstall Hill form must be con- 

 sidered as the type of the species. '^ 



As regards the Humbleton variety, I admitted that it was 

 closely related to Strophalosia Cancrini, De Verneuil, a Permian 

 species occurring in Russia; M'Coy, however, without giving 

 any satisfactory reasons, states that he entertains '^ little doubt " 

 of both being the same species J. I here speak of the Humbleton 

 variety, because it is the one which 1 suspect he had before him 

 when making the statement quoted. 



My attention having been again drawn to the present species ; 

 and as I cannot subscribe to the opinion just stated, I have con- 

 sidered it necessary to reopen the question as to its identity with 

 S. Cancrini f more particularly as De Koninck, having examined 

 a specimen from Ust-Joschuga in Russia, and compared it with 

 a Zechstein fossil from Gera in Germany, has expressed himself 

 similarly to M^Coy in his ' Monographic' (p. 108). I regret not 

 having been myself able to examine any Russian type-specimens 

 of S. Cancrini ; but I think I shall be able, by means of the 

 descriptions which De Verneuil, De Koninck and Count Key- 

 serling have given of it, to substantiate in a great measure the 

 view which I entertain on the question at issue. 



Strophalosia Morrisiana, taking the Tunstall Hill specimens 

 as its type, may be described as follows : — General form flatly 

 concavo-convex ; transversely elliptical. Large valve slightly con- 



* British Palaeozoic Fossils, p. 458. 



t Monograph, pp. 100 & 101. pi. 12. figs. 18, 19, 20, 21, 22, 23, 24, 25, 

 29, 30. Numbers 18 and 19 refer to the type-specimens ; the remaining 

 numbers to the Humbleton form, which I designated var. Humbletonensis, 

 stating at the same time that *' in case it should be found to be a di- 

 stinct species, the varietal should stand for the specific name." 



:J: M'Coy, op. cit. p. 457. 



