Victorian Fossi/s, Part XFI. Ill 



Observations. — Tliis spirifer has marked chtiracters of its own 

 which make it easily separable from tlie other Victorian Silurian 

 spirifers, namely, S. plicatellus, L. sp., var. macropleura, Conrad; 

 S. sulcatus, Hisinger, sp. ; and .S'. 7;f/7fl7;?e//os«s, J. Hall, var. 

 densilineata, Chapm. The nearest related form to the present 

 species is .S'. concinnus, J. Hall,i a spirifer of the sub-orbicularis 

 type from the Lower Helderbergian of N. America. From .S'. con- 

 cinnus the Lilydale species is separated by the smaller number of 

 ribs, which vary from 8 to 10, against 12 to 14 in the Lower Helder- 

 berg form. 



The Bohemian Silurian species, Spirifer viator, Barrande,- 

 approaches our form in the young stage, but in the ephebic and 

 gerontic conditions it has a remarkably large and salient mesial 

 fold. Moreover there are fewer ribs in that species; that is, 6 to 

 7 on each side of the mesial fold and sinus. 



Another somewhat related species is McCoy's Spirifer bijiif/osuM. 

 which occurs in the Wenlock Shale of Ireland.-^ So close is its 

 resemblance to the Victorian fossils in many points that the writer 

 had previously tentatively referred the latter to McCoy's species. 

 In the. number of the ribs the Irish species more nearly agrees with 

 ours, being 10 to 12 on each side as compared with the Victorian 

 with 8 to 10. The deep dividing groove of the mesial fold in 

 S. bijngosns is sufficient distinction, however, to .specifically separate 

 our Victorian specimens. At the same time it is extremely interest- 

 ing to note the double relationship of the two widely separated 

 brachiopod faunas of tlie British Wenlockian Series and the Lower 

 Helderbergian of N. America, with the Victorian Yeringian strata. 



At a casual glance, Mr. W. S. Dun's Devonian species S. pitt- 

 mani* from N. S. Wales, might easily be mistaken for .S'. lilydalensis. 

 The two forms belong, however, to separate groups. The ostiolate 

 group to which -S'. pittmani and .S'. yassensis must be referred, have 

 a smooth sinus and fold; while S. lilydalensis and the other related 

 forms of the sub-orbiculate group have the mediiin area striated or 

 plicated. 



Occurrence. — Well-preserved casts and moulds are often found in 

 the brown mudstone of the Lilydale district. The cotype of the 

 brachial valve Avas collected and presented by R. H. Annear, Esq., 



1 Pal. N. York, vol. iii., lS.o9, p. 200, pi. xxv., fifjs. -la!, and pi. xwiii., fij,'. 7. See also H.ill 

 and Clarke, ibid, vol. viii., pt. ii., 1S94, pi. xxx., fi-rs. 1, 2. 



2 Systi'uie .Silurien du centre de la Boheme, vol. v., 1879, pi. vii., fiy:s. 411 ; pi. ixxiii., fiys. 

 iii., 1-8; pi. xxiv., %. vi. 



3 S.viiopsis Silurian Fossils Ireland, 1846, p. 36, pi. iii., fig. 23. See also Davidson, Hrit. Sil. 

 Brach. (Pal. Soc), pt. vii.. No. 1. 1866, pi. x., fig.s. l.S, and pt. vii., No. 2, 1867, p 89. 



4 Dun. W. S. Rec. Geol. Surv. N. S. Wales, vol. vi., pt. 4, 1904, p. 320, pi. Ixi., figs. 4, 4a, M, 



