3S BRITISH PERMIAN BRACHIOPODA. 



all the peculiarities of its internal organization (figs. 5 and 11). Although correctly 

 described in 1848 and subsequently, it has nowhere been properly illustrated, for Professor 

 King's figures were evidently taken from very imperfect material. The species was also 

 discovered at Possneck, in Germany, by Baron Schauroth, who published some illustrations 

 of it in his first ' Beitrage/ 1 



Professor King is of opinion that the shell under description should be referred to 

 General Helmersen's Aulosteges? on account of the rudimentary area visible in some 

 examples, but this appearance seems to be more deceptive than real in the greater number 

 of specimens ; nor have I any grounds to suppose that the narrow fissure observable in 

 some specimens was covered by a deltidium, and the internal details, although slightly 

 different, are essentially the same as those peculiar to Produdus ; and Professor King 

 seems to be somewhat imbued with the same opinion, since he states, in his paper in the 

 'Annals' (1856), "I have represented the interior of the small valve of (?) Aulosteges 

 umbonittatus, on which it will be seen these structures (the reniform impressions) are 

 situated as in Produdus'' 



Sub-Genus — Strophalosia, King. 

 (Introduction, Vol. I, p. 115, 1853.) 



The identification or fixing of the species to which our English Strop/ialosias should 

 belong has given rise to considerable difference of opinion. I have therefore used every 

 effort in my power, in the hopes of arriving at a satisfactory conclusion, by a prolonged 

 examination not only of a vast number of specimens of our British and foreign equivalents, 

 but also by a direct correspondence and discussion with those who have studied the 

 subject with most attention. 3 



It must, however, be confessed that I have experienced considerable uncertainty and 

 difficulty in arriving at a conclusion relative to some of the points upon which the 

 difference of opinion principally prevails, and would therefore invite the reader to satisfy 

 himself before adopting the suggestions here proposed. Some authors would divide the 



1 ' Ein Beitrag zur Fauna des Deutschen Zechsteingebirges,' 1853. 



2 Professor King considers the sub-genus Aulosteges to be represented by the following species : 

 A. Wangenheimi, Vern. and Keyserling, sp., P. umbonillatus, King, and Sti-ophalosia tholus, Keyserling 

 (in Schrenk's 'Reise durch die Tundren der Samojeden,' vol. ii, p. 103, p. ii, figs. 18 — 21, 1854. 



3 The authors whom I have particularly consulted are Professor King, Mr. Howse, Mr. Kirkby, 

 Count A. Von Keyserling, Professor L. de Koninck, Dr. Geinitz, and Baron Schauroth ; but it has been 

 impossible to arrive at a unanimous conclusion, probably from the different manner in which a species is 

 viewed, some considering certain differences of specific value, while others view the same as accidental, or 

 at most varietal. 



