95 
It will be observed, in the first j)lace, that the ridges and tubercles arc 
very plainly visible on the cast, notwithstanding the inhospitable matrix con- 
taining it. In the second place, the relative thickness of the test is exemplified 
by the vacuity between the cast and surrounding matrix. Within this vacuity, 
but impossible to be shown on the plate, arc a number of projections from the 
bosses, showing that there w'ere particularly strong portions of the plates, 
reaching and indenting the matrix around. These are visible, and, I take it, 
represent what would have been the external appearance of the calyx wlien 
perfect. Moreover, by turning the fossil about in various directions, so as to 
admit light between the cast and the matrix, the surface of the latter can bo 
seen to be sufficiently undulating to correspond with the various inequalities 
visible on the surface of the former. These points admitted, it is impossible to 
unite the present fossil with that figured liy Sir P. M‘Coy, in which the test is 
jireserved, or those of T. Clarkei, of a similar nature, given in the present plates. 
This is the only sjiecies of Trihrachiocrinns in which any trace of the 
arms has been observed ; but, from causes mentioned above, it is impossible 
to give details regarding them. The first costals appear to be succeeded by 
two others, followed by an axillary costal, which supports two arm-1 )ranches. 
Localitu and Horizon, — Nowra, Co. St. Vincent {The late Uev, JF. 13. 
Clarke) : — Nowra Grit, Upper Marine Series. 
TniBRAcniociiiNus corrugatus, Ualle. 
PI. XVI, Pigs. 5-10. 
TrlhrachiocrdnilS oorrugakis, E.atte, Proc. Linn.Soc. X. H. Wales for 18SI [1SS5], IX, Pt. I 
p. 458, t. G8. 
Trihracllioerinus corrngatus, Wachsmuth and Springer, Eevision of the Palopoorinoidca, 
1885,Pt.III(l),t.6,f.5; 1886, Pt. Ill, (2), p. 251 (175). 
Trihrachiocrinus corrngatus, Eatte, Proc. Linn. Soe. X. S. AVhiles for 1886 [1887], I (2), 
Pt. 4, p. 1069. 
Sp. char . — Calyx globose, of medium size, symmetrical ; plates thick ; 
greatest periphery at about the basi-radial suture ; dorsal surface gently 
convex, and depressed around the columnar centre ; ventral surface depressed ; 
all sutures wide and deep ; infra-basal plates forming a shallow, wide, 
saucer-like cup, concave in the centre, which is visible in a side view when 
the calyx is placed in its normal position. PentagoEal basal wide and large. 
Azygous plate flatter than in the type species, and relatively extending higher 
Ua 01—92 F 
