SPHIEREXOCHUS .MIRUS. 151 



Genus SPHIEREXOCHUS, Beyrich. 

 1. Sphserexochus mirus, Beyrich, 1845. 



1840. Calymene clavifrons, Hisiuger, Leth. Suec, suppl. ii, pi. xxxvii, fig. 1. 



1845. Sphserexochus mirus, Beyrich, Ueber bohm. Trilob., p. 21. 



1846. Sphierexoclius mirus, Barraude, Not. prelim., p. 48. 



— Sphierexoclius mirus, Beyrich, Untersuch. iib. Trilob., pt. ii, p. 5, pi. i, fig. 8. 



? 1846. Sphierexochus calvus, M'Coy, Synops. Silur. Foss. Irelaud, p. 44, pi. iv, fig. 10. 



1847. Sphierexoclius mirus, Corda, Prodr. bOhm. Trilob., p. 138, pi. vii, fig. 72. 



1853. Sphierexochxis mirus, Barrande, Syst. Silur. Boheine, vol. i, pi. xlii, figs. 11, 18. 



— Sphierexochus mirus, Salter, Mem. Geol. Surv., dec. vii, pi. iii, figs. 1 — 15. 



1854. Sphierexoclius angustifrons, Angelin, Pal. Scand., pp. 36, 75, pi. xxii, fig. 8 ; pi. xxxviii, tig. 16. 



— Sphserexochus mirus, Morris, Cat. Brit. Foss., 2nd ed., p. 115. 



1857. Sphserexochus mirus, Nieszkowski, Archiv Naturk. Liv.-Est.-Kurl., ser. i, vol. i, p. 596. 



1858. Sphierexochus mirus, Schmidt, ibid., p. 189. 



1860. Sphierexochus clavifrons, Eichwald, Leth. Ross., p. 1401. 



1864. Spluerexochus mirus, Salter, Mon. Brit. Trilob., p. 76, pi. vi, figs. 1 — 6. 



1873. Sphierexoclius mirus, Salter, Cat. Camb. Silur. Fuss. Woodw. Mus., p. 131. 



1875. Spheerexoclius mirus, Baily, Char. Brit. Foss., p. 40, pi. xiii, figs. 10 or, b. 



1877. Sphierexoclius mirus, Woodward, Cat. Brit. Foss. Crust., p. 58. 



1878. Sphierexochus mirus, Nicholson and Etheridge, Mon. Silur. Foss. Girvan, fasc. i, p. 107, 

 pi. vii, fig. 20. 



1881. Spluerexoclms angustifrons, Schmidt., Rev. Ostbalt. Silur. Trilob., pt. i, p. 189, pi. ix, figs. 

 17 a, b; pi. xvi, fig. 38. 



1884. Sphierexochus mirus, Tornquist, Undersokn. Siljans. Trilobitf. (Sver. Geol. Undersokn., 

 ser. C, no. 66), p. 20. 



1885. Sphxrexochus minis, Lindstrom, Forteckn. Gotl. Sil. Crust. (Ofv. K. Svensk. Vet. Akad. 

 Forhandl., no. 6), p. 46. 



1888. Sphierexoclius mirus, Wigand, Zeitschr. deutsch. G-eol. Gesell., vol. xl, p. 87, pi. x, figs. 



13 a, b. 

 1899. Sphierexochus mirus, Mem. Geol. Surv., Silur. Rocks Brit., vol. i, Scotland, pp. 504, 510, 



674, 689. 



Remarks. — It has been attempted to separate the Ordovician representatives of 

 this species as distinct, and Schmidt (pp. cit., p. 189) accordingly places them with 

 Angelin's species, 8. angustifrons. The basal lobes are said to be separated by a 

 space equal to only their own diameter, instead of by a space more than half as 

 wide again, as in the Silurian examples. But this distinction seems to break down 

 in the case of the Grirvan specimens, for there are glabellas from Craighead with the 

 basal lobes as widely distant as many Silurian examples. It does not therefore 

 seem to be a sufficient character for a specific distinction, the range of variation 

 being wide. It is, however, possible that in the pygidium Ave may find other 



