ISOTELUS. 



161 



caudal fascia is half as broad as the limb and coarsely striated throughout. The other 

 figures in PI. XVI will sufficiently shew the characters of the species. 



Locality. — Llandeilo Flags of Penrhiw, four and a half miles north-east of Builth. 

 Collected by Miss Thomas, of Penkerrig, and presented to the Mus. P. Geol. several years 

 back. The species is abundant at Gilwern, near Llandrindod ; and also at Min Cop, 

 Meadowtown, in the Corndon district, whence the species was named. 



As reference has been made under the last two or three species to subgenera not 

 yet distinctly recognised in Britain, I subjoin a figure of the subgenus Ptychopyye, 

 Angelin, and also one of Megalaspis, to shew the extravagant form sometimes assumed 

 by the latter group. 



Fig. 34. 



Fig. 35. 



Asaphus {Ptychopyge) lotus, Angelin. 



' Pal. Suec.,' t. xxxi, Fogelsang, Scania. 



Lower Silurian. 



As. (Megalaspis) extenuatus, Angelin. 

 ' Pal. Suec.,' t. xi, fig. 1, Ostrogothia. L. Silurian. 



IsoTELUs, Be Kay., 1824. 



AsAPHUS (IsoTELUs) GiGAS, De Kay. PI. XXIV, figs. 1—5 ; PI. XXV, fig. 1 {var.). 



Asaphus platycephalus, Stokes. Trans. Geol. Soc, 1st series, vol. viii, p. 208, 



pi. xxvii, 1822. 

 IsoTELUs GIGAS and I. PLANUS, De Kay. Annals of Lyceum New York, vol. i, p. 176, 



pis. xii and xiii, fig. 1, 1824. 

 Asaphus gigas, Dalman. Palseadae, p. 71, 1826. 

 IsoTELUS GiGAS, Green. Monograph Tril., 67. I. planus ; I. stegops, lb., pp. 



68 — 71. I. CYCLOPS; I. MEGALOPS, Ibid., 1832. 

 Brongniartia isotela, Eaton. Geol. Text-book, pi. ii, fig. 19, 1832. 

 21 



