Upper Silurian.] PALEONTOLOGY OF VICTORIA. [ Mollusca. 
Prats XLVII., Fias. 1, 2. 
SPIRIGERINA RETICULARIS (Liv. sp.). 
[Genus SPIRIGERINA (p’Ors.). (Sub-kingd. Mollusca, Class Palliobranchiata, Order 
Brachiopoda. Fam. Spiriferide.) 
Gen. Char.—Shell oblong, marked with radiating dichotomous ridges; beaks close, or 
showing a small round opening close under the beak, separated from the hinge-line by a 
deltidium of two pieces ; internally the receiving valve has two short diverging cardinal teeth 
(one on each side of the deltidial space); the entering valve has a very short mesial septum, 
and two long apophyses obliquely coiled in large flattened conical spires, base of each nearly 
parallel with the plane of the margins of the valves, apices near the middle of inner surface of 
the entering valve. In receiving valve the two muscular impressions are very large, occupying 
nearly half the space of the interior; the pallial trunks are very simple, with few slender 
branches. } 
Descriprion.—Elongate, ovate, or sub-triangular from the hinge-line extending 
into compressed ears nearly as wide as the shell, (small varieties often nearly 
orbicular) ; in ordinary adult specimens the receiving valve is nearly flat, convex at 
the beak, which is small and prominent, becoming gradually concave towards 
the margins, which are more or less reflected; the opposite valve very gibbous 
along the middle, gradually sloping towards the margin; surface covered with 
strong rounded or sub-angular ridges, irregularly branching and increasing in 
thickness towards the margin, separated by deep sulci rather less than the ridges in 
width, both crossed by irregular, strong, scaly lines of growth, averaging five or six 
in 2 lines at 6 lines from the beak (varying from four to seven). Average length, 
a little over 1 inch; proportional width, 485, to +93; depth of both valves, from 
382; to 73°; ; in specimens four lines long the valves are evenly convex and nearly 
orbicular; the entering valve litttle more tumid than the receiving one; cast of the 
beaked valve showing a deep oblique pit on each side of the beak for the hinge- 
tooth ; a large, broad, oval, muscular impression, faintly divided down the middle 
and obscurely radiated, occupies the middle of the rostral half, round this is a space 
closely set with small irregular papilla; external margin smooth. 
REFERENCE.—Anomia reticularis, Lin. Syst. Nat. = Terebratulites priscus, 
Schlot. Petref. und Nachtr.= 7. erplanatus, Id.= Terebratula affinis, Sow. Min. Con. 
and Sil. Syst. t. 6, f. 5.= A. aspera, Sow. Sil. Syst. t. 12, f. 5.=A. orbicularis, Sow. 
Sil. Syst. t. 19, f. 3, 4. 
This is a very variable shell, but the above description indicates 
the most common and characteristic variety. It varies, Ist, in the 
conyexities of the valves, both as to degree, distance from the 
beak at which it is greatest, and equality; some small varieties, 
and the young at all times, having the valves almost equally and 
evenly convex: 2nd, in form, some, particularly the young and 
the small varieties, being nearly orbicular, others being elongate 
and nearly triangular from the width of the hinge-line and 
DEC. V. [ 25 ] D 
