92 INTRODUCTION. 



retained. The author also forms two divisions in his genus, viz. striata and Icevis; 

 A. reticularis, and aspera, being the types of the first, A. prunum of the second. 



Geol. range. — The genus first appeared during the Silurian period, and continued in 

 the Devonian epoch, above vi^hich no authenticated example has been observed. 



Examples: A. reticularis, Linn. sp. ; aspera, Schl. ; spinosa, D'Orb. ; marginalis, 

 Dalman, sp. ; comata, Barr. ; prunum, Dalman,i &c. 



Family— KONINCKINID^. 



Animal unknown; shell free; valves unarticulated ? oral arms supported by two 

 lamellse spirally coiled. 



Obs. Only one genus and species is at present known, which had formerly been classed 

 among the Productida, but from which it has been since removed, on account of its 

 peculiar internal organisation. I have placed it directly after the Spiriferidcs, on 

 account of the spiral lamellae observed in its interior, which bear some resemblance to 

 those of Atrypa. 



Genus — Koninckina, Suess, MS., 1853. 



Type—K. Leonhardi, Wissmann, sp., 1841. Int., PI. VIII, figs. 194—198. 



Pkoductus, Wissman,^ MUnster,^ Klipstein, Be KonincJc,'^ &c. (part.) 



Shell nearly circular, ineqviivalve, compressed; larger or ventral valve convex or 

 gibbous, with a slight longitudinal depression ; beak considerably incurved, with auricular 

 expansions ; smaller or dorsal valve concave, following the curves of the other ; surface 

 smooth ; no area or deltidium ; valves unarticulated ? in the interior of dorsal valve a 

 mesial ridge extends from the cardinal process to the frontal margin ; arms or oral 

 appendages supported by a spiral calcified lamella ? 



Obs. All the authors who have described this remarkable shell have placed it in Pro- 

 ductus, although it possesses, in reality, none of the internal characters peculiar to that 

 genus. Dr. Klipstein^ has observed that it possessed internal traces of the spiral arms, 

 and figures large spiral ridges. Having had an opportunity of examining, along with 



^ M. d'Orbigny places this species into his genus Atnjpa (Prod., p. 37), and it must likewise be 

 observed, that the French author's genus Atrypa is made up of a strange assemblage of dissimilarly 

 organised forms, and which do not possess the characters assigned to them in vol. iv of the ' Pal^ont. 

 Fran?.;' most of M. d'Orbigny's Atrypa are shells with spirals, and belong to the same section into 

 which he places tumida, viz., spirigera. 



2 Beitr. zur Petrefacten, Von Miinster, vol. iv, p. 18, pi. vi, fig. 21, 1841. 



3 Ibid., p. 68, fig. 24, P. dubia? 1841. 



* Recherches sur les Animaux Fossiles, 'Mon. des Productus,' p. 167, pi. xvii, fig. 4, 1847. 

 ^ Beitr. zur Geol. Kenntn. der Ostl. Alpen., p. 236, pi. xv, figs. 20 and 21ff, Prod, alpina, 1845. 



