ILI^ENUS MURCHISONT. 6b 



8. lllsenus macallumi, Salter, 1867. Plato IX, figs. 8, 9. 



1867. lllsenus (Bumastus) maccallumi, Salter, Moil. Brit. Trilob., p. 210, pi. xxviii, fig. 1 ; pi. xxx, 



figs. 2, 3. 

 1877. lllsenus (Bumaslus) maccallumi, Woodward, Cat. Brit. Foss. Crust., p. 41. 

 1879. lllsenus macallumi, Nicholson and Eth.eri.dge, Mon. Silur. Foss. Grirvan, fasc. ii, p. 162, 



pi. xii, fig. 2. 

 1882. Ilhenus macallumi, Holm, Svensk. Art. Illamus (Bih. K. vet. Akad. Handl., vol. vii, No. 3), 



p. 54. 

 1899. lllsenus maccallumi, Mem. Geol. Surv., Silur. Bocks Brit., vol. i, Scotland, pp. 529, 673. 



Uemarlcs. — This curious species lias only so far been found at Mnllocli Hill, from 

 which locality Salter's types were obtained. Nicholson and Etheridge {<>/>. cit.) 

 also figure an example from this place. A specimen of a head-shield in Mrs. 

 Gray's collection shows, in addition to the characters mentioned by Salter, that 

 the fixed cheeks are very narrow, that the eyes are situated about halfway up 

 the sides of the glabella, and the distance between them is slightly less than 

 the length of the head-shield. A faint keel runs along the middle of the glabella, 

 which is about half the length of the head-shield. 



Collections.— Mm. Gray (f. M.) ; Mnseiun of Practical Geology. 



Horizon and Locality. — Mulloch Hill Group (L. Llandovery) : Mulloch Hill. 



9. Illamus murchisoni, Salter, 1852. Plate IX, figs. 10—12. 



1848. lllsenus rosenbergii, Salter (non Bichwald), Mem. Ceol. Surv., vol. ii, pt. 1, pi. v, figs. 6 — 8. 



1849. lllsenus murchisoni, Salter, Mem. Geol. Surv., dec. ii, art. ii, p. 4. 



1852. lllsenus murchisoni, Salter, in M'Coy's Synops. Pal. Foss. Woodw. Mus., fasc. i, appendix, 



p. iv (description only). 

 1854. lllsenus murchisoni, Morris, Cat. Brit. Foss., 2nd ed., p. 110. 



1866. Ilhenus murchisoni, Salter, Mon. Brit. Trilob., p. 201, pi. xxvi, fig. 1 ; pi. xxx, fig. 7. 

 1877. lllsenus murchisoni, Woodward, Cat. Brit. Foss. Crust., p. 41. 

 1882. Ilhenus murchisoni, Holm, Svensk. Art. lllsenus (Bih. K. vet. Akad. Hand]., vol. vii. No. 3), 



p. 46. 



Remarks. — Certain pygidia from Craighead in Mrs. Gray's collection may 

 probably be referred to Salter's species /. murchisoni. These pygidia are semi- 

 oval, nearly as long as broad, rather flat and not bent down posteriorly. The 

 axis is broad, projects slightly on the front edge and is scarcely defined at all 

 by furrows or even by indentations on the front edge. The fulcrum is approximate, 



9 



