262 Prof. W. King's Notes on Permian Fossils, 



abnormal form of the genus ; for no species that I am aware of 

 possesses a truncated beak. I found two or three specimens 

 with a fragment of stone (? clay-slate), to which they adhered, 

 still attached to the truncated surface of the umbone : when 

 chipped out it left a deep groove on the truncation. Froductus 

 Schaurothianus thus agrees with most species of Strophalosia, — a 

 circumstance which might induce some to suppose that it be- 

 longs to the last-named genus ; but I have failed in discovering 

 any traces of teeth or of an area. Being an attached shell, this 

 species affords another argument against the opinion that the 

 Producti adhered to foreign bodies by means of fibres passing 

 out of their anterior opening, as advocated by De Koninck. 

 Attached species, such as the present, evidently adhered to 

 foreign bodies by their umbone in the same way as oysters, &c. 

 I suspect that some species moored themselves by means of their 

 spines, like Strophalosias ; while others, such as Productus gigan- 

 teiiSj remained free, resting on their large convex valve, as is the 

 case with Pecten Jacobaus. 



The median depression in Productus Schaurothianus is seldom 

 exactly in the middle, which causes the large valve to be unequally 

 lobed. The costules number about five in a quarter of an inch 

 at the anterior margin. No spines are visible on either valve. 

 None of the specimens that have occurred to me exceed ^ths of 

 an inch in diameter. I am not aware of its occurring in any 

 other locality than Ropsen. 



Genus Aulosteges, Helmerson. 

 ? Aulosteges umhonillatus= Productus id.^, King. PI. XII. fig. 6. 



This singular species appears to be somewhat abundant at 

 Possneck, where its occurrence was first made known by 

 Schauroth, who has given some characteristic figures of it in his 

 first * Beitrag f.' I diagnosed it as being " subtriangular mar- 

 ginally,'' which is an error : it ought to have been described as 

 subquadrate, which may be seen by consulting the figures re- 

 ferred to in the note. 



From the circumstance of this species possessing some " ap- 

 pearance of an area," I ventured to state, in my Monograph, 

 that eventually it might be found to belong to Helmerson's 



* Vide Monograph of the Permian Fossils of England, p. 92. pi. 1 1 . 

 figs. 14-17. 



t Vide " Ein Beitrag zur Fauna des Deutschen Zechsteingebirges, mit 

 Beriicksichtigung von King's Monographic der Versteinerungen des per- 

 mischen Systems in England." (Aus dem Junihefte des Jahrganges 1853 

 der Sitzungsberichte der mathem.-naturvv. Classe der kais. Akad. der Wis- 

 senschaften [Bd. xi. S. 147] besonders abgedruckt.) 



