166 CARBONIFEROUS CEPHALOPODA OF IRELAXD. 



1883. MuNSTEROCERAs TEUNCATUM, A. Hijatt. Proc. Boston Soc. Nat. Hist., 



vol. xxii, p. 326. 



1888. GoNiATiTES TEUNCATUs, E. Etlieriihje. Brit. Foss., vol. i, Palaeozoic, p. 313. 



1889. Glyphioceeas teuncatum, E. Holzapfel. Palseont. Abhaudl., Dames uud 



Kayser, vol. v, i, j). 26, pi. i, figs. 8, 9. 



1890. MuENSTEEOCEEAs TEUNCATUM, G. Steinmann und L. Duderlein. Elemente 



dor Paloeoutologie, j^t. 2, p. 393. 

 1895. GoNiATiTEs TEUNCATUS, G. JI. MoHoti. Proc. Liverpool Nat Field Club 



for 1894, p. 24. 



1897. Glyphioceeas teuncatum, A. H. Fourd and G. C. Crick. Cat. F«jss. 



Ceijh. Britisli Museum, pt. 3, p. 175, 

 fig. 82 (suture-line). 



1898. — — G. C. Crick. Traus. Linu. Soc, ser. 2, vol. vii, 



p. 108, pi. XX, fig. 19. 

 1900-1901. Goniatites TEUNCATUS, (?. JI. il/or/ow. "The Carboniferous Limestone of 



Anglesey," Proc. Liverpool 

 Geol. Soc., p. 52. 

 1903. Glyphioceeas teuncatum, Whcelton Hind. Brit. Assoc. Adv. Sci., Bel- 

 fast, 1902, p. 215 : " Life-zones 

 in the Carboniferous Rocks." 

 [Not 1854. Goiiiatites truncatun, F. A. Roemer, Palaiontographica, vol. iii, p. 94, pi. xiii, fig. 30. — 

 1884. Glyphioceras truncatum, A. Hyatt, Proc. Boston Soc. Nat. Hist., vol. xxii, p. 329.] 



Bescription. — Shell attaiuiug a considerable size, much compressed, discoidal, 

 involute ; the greatest thickness at about one-third of the height of the whorl from 

 the edge of the umbihcus, leather more than one-third of the diameter of the shell ; 

 height of outer whorl three-fifths of the diameter of the shell. Whorls from five to 

 six ; inclusion nearly complete ; umbilicus small, shallow, from one-seventh to one- 

 ninth of the diameter of the shell in width. Whorl subipiadrang-vdar in section, 

 about one-third higher than wide ; indented to nearly one-third of its height by the 

 preceding whorl. Periphery more or less flattened or subtruncate, sometimes with 

 perceptible subangular margins ; sides very slightly convex, flattened ; umbilical 

 zone scarcely distinguishable, gently rounded, merging into the sides of the shell. 

 Body-chamber occupying rather more than a complete whorl ; aperture with a deep 

 lateral, and a deep peripheral sinus. Chambers rather deep, eleven or twelve in a 

 whorl ; suture-line as in PI. XLIV, fig. 2 r, and PL XLIX, fig. 1 1. 



Test thin, with fine siginoidal lines of growth which Ijocome oUsolele in large adult 

 specimens. A few constrictions, sometimes strong, sometimes feeble, are j)resent in 

 all stages of growth (PI. XLIII, fig. 5 ; PI. XLIV) ; these are broiul and shallow, and 

 occur apparently at irregular intervals; they are ver^' conspicuous upon the cast, 

 but are scarcely seen upon the test, which seems to fill them up almost entirely. Li 

 a very large adult shell, the surface of which is much eroded, there are obscure 

 transverse folds near the aperture representing the lines of growth, and these are 

 seen in other specimens, large and small, under favourable conditions of preserva- 



