CEPHALOGRAPTUS. 285 



that of the genus Phyllograptus, but also that of Crypto graptus. This biserial 

 mimetic form may eventually be shown to belong to a new sub-genus which is 

 related to Didymograptus as Phyllograptus is to Tetragraptus (Mimograptus, 

 Lapw. MS.). 



Horizon and Localities. — Glenkiln Shales. 



S. Scotland .- Belcraig; Dobb's Linn; Glenkiln Burn; Carrifran Burn. 



Associates, etc. — P. (?) phylloides is of fairly common occurrence in a band in 

 the Nemag. gracilis zone at Belcraig Burn, where it occurs associated with the zone 

 fossil, Dicellog. sextans, Orthog. Whitfieldi, Gryptog. tricomis, etc. It has also been 

 found, though less abundantly, at the Glenkiln Burn, and at Dobb's Linn, etc. 



Collections. — Sedgwick Museum, Lapworth, and the Authors. 



Group II. Oephalograptus, Hopkinson. 



Petalograpti in which the polypary is triangular or fusiform, proximal end 

 very protracted. Sicula largely exposed, completely visible in both obverse and 

 reverse aspects. Septum incomplete. Thecas approximately straight, with 

 concave apertural margins which are horizontal in compressed examples. 



Cephalograptus cometa (Geinitz). Plate XXXII, figs. 10 a — d. 



1852. Diplograpmos cometa, G-eiiiitz, Die Gkaptolithen, p. 26, pi. i, fig. 28. 



1853. Diplogrwpsus cometa, Richter, Zeilsclir. d. deutsch. geol. Gesellsch., vol. v, p. 457, pi. xii, 

 figs. 16, 17. 



1867. Dlplograjjsus tubulariformis, Nicholson, Geol. Mag., vol. iv, p. 109, pi. vii, fig. 15. 



1868. Dijalograpsus cometa, Carruthers, Geol. Mag., vol. v, p. 131, pi. v, fig. 4. 



1869. Cephalograptus cometa, Hopkinson, Journ. Quek. Micros. Club, p. 159, pi. viii, fig. 14. 



1873. Cephalograptus cometa, Lapworth, Geol. Mag., vol. x, p. 555, and Proc. Geol. Assoc, vol. iii, 

 p. 167. 



1876. Cephalograptus cometa, Lapworth, Cat. West. Scott. Foss., pi. ii, fig. 31. 



1877. Cephalograptus cometa, Lapworth, Graptolites of Co. Down, p. 132, pi. vi, fig. 4. 

 1878 — 79. Diplograptus cometa, Tornquist, Geol. Foren. Forhandl., vol. iv, p. 456 



1882. Cephalograptus cometa, Tullberg, Bihang till k. Svenska Vet.-Akad. Handl., vol. vi, no. 13, 



p. 15. 

 1890. Diplograptus cometa, Geinitz, Graptolithen des k. niineralog. Mus. Dresden, pi. a, fig. 47. 

 1893. Cephalograptus cometa, Tornquist, Structure of some Diprionicla?, Acta Univ. Lund., vol. xxix, 



p. 11, figs. 36—41. 

 1897. Cephalograptus cometa, Elles, Quart. Journ. Geol. Soc, vol. liii, p. 204, pi. xiii, figs. 10 — 16. 

 1897. Bipjlograptus cometa, Tornquist, Diplog. and Heteroprionidse of Scanian Bastrites Beds, 



Acta Reg. Soc. Physiog. Lund., vol. viii, p. 14, pi. ii, figs. 8 — 14. 



Polypary elongate, fusiform, acicular, 1 — 4 cm. in length, very slender 

 proximally, but widening gradually to a maximum breadth of 2*5 mm., 

 which is attained opposite the aperture of the first theca, maintaining this 



