274 



BRITISH GRAPTOLITES. 



Petalograptus palmeus s.s. (Barrande). Plate XXXII, figs. 1 a — J. 



1850. Graptolithu8 palmeus, Barrande, Grapt. cle Boheine, p. 59, pi. iii, figs. 1 — 7. 



1851. Petalolithu8 palmeus and parallelo-costatus, Suess, Ueber Bohmische Graptolithen, pp. 20, 21, 

 pi. viii, figs. 1, 2, 4. 



1852. Diplograptus palmeus, Geinitz, Die Graptolithen, p. 21, pi. i, figs. 5 — 19. 



1853. Diplograptus palmeus, Richter, Zeitsch. d. deutsch. geol. Gesellsch., vol. v, p. 455, pi. xii, figs. 

 8—10. 



1870-1880. Diplograptus palmeus, Zittel, Traite de Paleont., vol. i, p. 305, fig. 214 d, e. 



1880-1881. Diplograptus palmeus, Linnarsson, Geol. Foren. Furhaudl., vol. v, p. 522, pi. xxiii, figs. 



26—28. 

 1887. Diplograptus palmeus, Toruquist, Geol. Foren. Forhandl., vol. ix, pp. 478 — 481. 

 1890. Diplograptus palmeus, Geiuitz, Graptoliten des k. mineralog. Mus. Dresden, p. 26, pi. a, 



figs. 39, 41—43. 

 1893. Diplograptus palmeus, Tomquist, Structure of Some Dipriouidse, Acta Univ. Lund., vol. xxix, 



p. 9, figs. 29—35. 

 1897. Petalograptus palmeus s.s., Elles, Quart. Jouru. Geol. Soc, vol. liii, p. 193, pi. xiv, figs. 1 — 4. 

 1897. Diplograptus palmeus, Toruquist, Diplog. aud Heteropriouida; of Scanian llastrites Beds, 



Acta Reg. Soc. Physiog. Lund., vol. viii, p. 10, pi. i, figs. 25, 26. 



Polypary from 1 — 3 cm. in length, widening at once to a breadth of 2'5 — 8 mm., 

 and this being maintained the polypary has snb-parallel sides, but is rounded 

 off distally. Thecse twelve to fourteen in 1 mm., alternate, with an average 

 length of 2 mm., three times as long as wide, overlapping two thirds of their 

 length ; apertural margins concave, oblique. 

 Description. — The sicula has usually a length of about 2 mm., and extends up 

 to the base of th. 3~ ; it is therefore longer relatively to the theca3 than that of 



Petalog. folium. In the Gala-Tarannon examples the 

 virgella seems to have been particularly stout and 

 strong, but in the examples occurring at lower 

 horizons this spine is either wanting altogether, or 

 is only represented by a short fragment. 



Th. I 1 originates close to the aperture of the 

 sicula, and grows outward and upward at once, and 

 its axial line makes a very decided curve ; th. I 3 

 grows in a manner very similar to that of Petalog. 

 folium except that its curvature is greater and is 

 developed earlier than in that species, so that the 

 sicula is not free for so large a fraction of its length 

 on the right side. In the obverse aspect of the poly- 

 pary the sicula is apparently free for about one 

 quarter of its length on the right side, but in the 

 reverse aspect the aperture is seen to the left only, the remainder being concealed 



Figs. LS8 a and b. — Petalograptus 

 palmeus (Barr). 



« f%> 



t 



a. Complete specimen, reverse aspect, 



but showing sicula. Nat. size. 

 Zelkovice, Bohemia. Figured, Elles, 

 Quart. Journ. Geol. Soc, liii, pi. xiv, 

 fig. 1. Coll. Brit. Museum (Nat. 

 Hist.). 



b. Reverse aspect of young specimen, 



showing' sicula pressed through. 

 Dobb's Linn, Birkhill Shales. Coll. 

 Geol. Survey of Scotland, Edin- 

 burgh. 



