DAVIDSON — SCOTTISH CARBONIFEROUS BRACHIOl'ODA. 
23 
hinf*e-plato is (lccj)ly divided, and supports two slender curved lamcUse, to 
which the spirally coiled lleshy ond anus (directed inwards towards the con- 
cavity of the dorsal valve) we're partially fixed. In tlie interior of tiie ventral 
valve the teeth are sujiported by dental plates, between whieii, and extending 
somewhat further down, are tiie muscular impressions [jrodaeed by (lie adduc- 
tor or occlusor, tiie devaricator, and pedicle muscles, wliile on the bottom of 
tlie dorsal valve may be seen tlu; four impressions formed by t he adductor, or 
occlusor muscle. Ovarian markings arc observable ou eitlier side of the 
muscular scars above described. 
Lign. 6. — Eliynclioiiella psittacea (recent). 
Fig. 2. — Interior of the Dorsal Valve. 
a a. Adductor, or anterior and posterior oc- 
clusor. 
», Sockets. 
c. Curved lamellae for tlie attachment of the 
oral arms. 
Fig. 1. — Interior of the Ventral Valve. 
a, Adductor, or occlusor muscular impression. 
r. Cardinal or divaricator ,, „ 
p, Ventral adjuster „ „ 
0, Ovarian spaces. 
d, Deltidiimi. 
t, Teeth. 
XIX. — RiiYNCHONELLA PUGNUS. Martin. PI. i., figs. 1, 2. 
Conchi/UolUJms anomites pngnus. Martin. Pctrificata Derbiensia, tab. xxii., 
figs. 4, 5, 1809; and Dav. Mon. Carb., p. 97, pi. xxii., figs. 1-15. 
The shells composing this species are either transversely ovate or oblato- 
dcltoidal, and wider than long. The dorsal valve is usually more or less 
gibbous, most elevated near the front, and evenly convex at the umbone ; the 
mesial fold is large, and more or less prominent ; the ventral valve is less con- 
vex than the opposite one, with a sinus of moderate depth, commencing at a 
short distance from the beak, and extending to the front ; the beak is small, 
much incui'vcd, and contiguous to tlie umbone, each valve being ornamented 
with from nine to twelve ribs, wliich become obsolete as they approach the 
beaks ; from three to six oecujiy the fold and sinus. 
All the Scottish examples of this shell that I have hitherto seen were small, 
none having exceeded eight lines in length by about ten in width, whde some 
English specimens have measured as much as two inches both ways ; neverthe- 
less, the Scottish examples have all the characters of the full-grown shell ; but 
a variety from Carluke parish is comparatively wider and less convex than ano- 
ther found in Stirlingshire and elsewhere. 
At Mosside and Braidwood, in Lauarksliire, R. jtugnm is found at three 
hundred and sevcuty-five fathoms lower than the "Ell coal," also at Brown HiU, 
near Lesmahago ; in lleufrewshire, at Barrhead and Arden quarry, Thorulie- 
