75 
EuRYDESMA IIOBARTENSE, JollHSton. 
(Plate XVIII, Figs. 2 and 3 ; PL XX, Fig. 6 ; PI. XXI, Figs. 2 and 3 ; Plate XXII, 
Figs. 1 and 2 ; PI. XXIII, Fig. 5 ; PI. XXIV, Fig. 3; PI. XXV, Figs. 4 and .5.) 
PacJiydoMUS hobc(Ttensis, Johnston, Syst. Acc. Geol. Tas., 1882, PI. .xvi, fig. 2. 
(?) Huvydesinci covdcttci, Jolmstoji (?ton Morris), Ibid., PI. .xvii, figs. 2, 3, 3« and b. 
Leiomyalina antarctico , Freeh, Roemer’s Leth»a Pal., 1902, II, Lief. 4, p. 600, fig. a. 
Eu 7' y dcsniCl cordotn, Sussmilch, Proc. Linn. Soc. N. S. Wales, 1906, XXXI, Pt. 1, p. 175. 
Specific Characters. — Shell obliquely oblong-ovate ; valves convex, 
but not ventricose, may be produced ventrally ; uml)ones acute, overbangiug 
the lunule; umbonal slopes rounded, not steep. Lunule well marked, but 
not deeply excavate. Articulus as in E. cordatmn, but much less massive, 
the binge-plate narrow. Cinctures not observed. Adductor scars as described 
on p. 58. Retractor scars as in E. cordata. Sculpture concentric, no radii 
seen. 
Observations. — The separation of this shell from E. cordata is merely 
a question of degree — the general structure is the same, but all the parts are 
on a less massive scale. The valves are far less ventricose, the depth through 
the conjoined valves being not nearly as great as in E. cordata. An 
examination of the articuli as shown in figures published by Johnston and 
Erecb, mentioned in the synonymy, and those now published (PI. XX, fig. 0 ; 
PI. XXI, fig. 2), and comparison with those of corresponding regions in 
E. cordata (PI. XIX, fig. 5 ; PI. XX, figs. 2, 3, 5) will at once show the 
much less massive structures of the hinge regions in E. hobartense. 
Professor Boehm, during his visit to Tasmania, collected extensively 
from the Eurydesma beds, and noticed the similarity of Freeh’s 1902 
specimens to his own material.^ 
One of the specimens of this form furnishes the only example in which 
the large adductor impression is preserved — this is described on p. 58. 
Localities. — Maria Island, Tasmania — •Permo-Carboniferous, Lower 
Marine Series; Railway Cutting, near Belford, N. S. Wales (C. A. Siissmilch, 
JE. S. Dim, C. Cullen) — Permo-Carboniferous, Upper Marine Series. 
Collections. — Mining and Geological, Technological, and Australian 
Museums. 
* Boehm — Loc. cit., p. 297. 
