AGNOSTUS PISIFORMIS. 



Brogger in his description states that the Christiania form does not agree 

 precisely with Tullberg's figure and description, and in his figure the anterior lobe 

 of the glabella is less distinctly defined than in Tullberg's. 



Horizon and Localities. — Lower Lingula Flags : Tyn-y-groes and Cefn Deiddwr, 

 Mawddach ; Dolgelly ; ? St. David's. 



6. Agnostus pisiformis (L.). Plate I, fig. 12. 



1757. Entomolitus paradoxus y pisiformis, Linnoeus, Iter. Scan., p. 122. 



1821. Entomostracites pisiformis, Wahlenberg, Petr. Tel. Suec, p. 42, pi. i, fig. v. 



1822. Agnoshis pisiformis, Brongniart, Crust, foss., p. 38, pi. iv, fig. 4. 



1827. Battus pisiformis, Dalman, Om Palaead., K. Vet, Akad. Handl. (1826), p. 258, pi. vi, 



fig. 5 a — d. 

 1837. Battus pisiformis, Hisinger, Leth. Suec, p. 19, pi. iv, fig. 5. 

 1837. Battus pisiformis, Q spiniger, Hisinger, ibid., p. 20, pi. iv, fig. 6. 

 1852. Agnostus pisiformis, Angelin, Pal. Scand., p. 7, pi. vi, fig. 7. 

 1869. Agnostus pisiformis, Linnarsson, Om Vestergotlands Canib. och Sil. Aflagr., p. 81, pi. ii, 



figs. 50, 51. 



1879. Agnostus pisiformis, Brogger, Nyt. Mag. for Naturv., vol. xxiv, pi. vi, fig. 13 a, b. 



1880. Agnostus pisiformis, Tullberg, Agnostus-arterna, p. 25, pi. ii, fig. 14 a, b. 

 1882. Agnostus pisiformis, Brogger, Die Silur. Etagen 2 und 3, p. 55. 



1895. Agnostus pisiformis, Wallerius, Zone med Agn. laevigatus, p. 43. 



Although the typical form of this species appears to occur in Britain, the 

 specimens are much distorted, and I therefore give Tullberg's description and a 

 copy of his figure. 



" Crusta laevis. Limbus non angustus. Caput rotundatum, latum. Frons 

 non longa, biloba. Lobus anterior rotundatus. Lobus posterior supra medium 

 puncto elevato ornatus, postice rotundatus. Lobi basales subtriangulares. Genae 

 ante frontem linea separatee. Pygidium latum, rotundatum, bidentatum. Rachis 

 lineolis vix visibilibus triarticulata, postice fere rotundata. Articulus medius postice 

 puncto elevato prceditus. Lobi laterales pone rachin non separati, postice angustati. 



" Long. & lat. clypeorum, 5 mm." 



6 a. Agnostus pisiformis (L.), var. obesus, Belt. Plate I, figs. 13, 14. 



1867. Agnostus pisiformis, var. obesus, Belt, Geol. Mag., vol. iv, p. 295, pi. xii, fig. 4 a — d. 



1880. Agnostus pisiformis, var. socialis, Tullberg, Agnostus-arterna, p. 25. 



1882. Agnoshis pisiformis, var. socialis, Brogger, Die Silur. Etagen 2 \md 3, p. 56, pi. i, fig. 10 a — c. 



Head rounded, with narrow margin. Glabella conical, bilobed; anterior lobe 

 small and narrow in front ; posterior lobe wider than the anterior lobe, widens 



2 



