47G 
THE GEOLOGIST. 
V. — Axn-niis rLANO-suLOAXA. Phillips sp. PI. xii, figs. 10, 11. 
Spirifera pkino-nulcata, Pliillips, Geology of Yorkshire, vol. ii., p. 220, pi. x., 
fig. 15, 1S3G; aud Dav. Men. Carb., p. 80, pi. xvi., figs. 2-13,15. 
The shape of tliis shell is more often orbieular, the valves being equally deep 
and evenly convex, without sinus or fold, or with a sliglit mesial depression 
towards the front in one or botli valves. Tiie beak is small and incurved, with 
a minute foramen placed close to the umbone of the o])j)ositc valve. When 
perfect, the surfaces of l)ot]i valves are ornamented at intervals of less than a 
line, witii mimerous concentric semi-circular lamcHiform expansions, caeli jjlate 
being flat aud longitudhially striated. It is, however, rare to obtain specimens 
in wliich the plates arc in place, as they generally remain in the matrix from 
wlicnce the shell is detached. The interior arrangements are similar to those 
of A. amhigua. 
A. phtno-siilrafa does not appear to be a very common shell in Scotland ; it 
occurs at three luindred and forty-three fatlioms below the "EUeoal," and near 
Lcsmahago, in Lanarkshire. In Stirlin^sliire it occurs at Craigenglen. In Ren- 
frewslurc, at Arden quarry, Thornliebank, Barrhead, etc. ; in Ayrshire, at 
lloughwood and West Broadstone, near Beith. It has also been found in West 
Lotman. 
VI.— Athyeis RoYSSii. L'EveiUe. PI. xii, fig. 12. 
Spirifer de Roi/ssii, L'Eveille, Memoirs de la Societe Geologicme de France, vol. 
ii., p. 39, pi. ii., figs. 18-20, 1835; and Ai////ris lloj/ssU, Dav. Mon. Carb., 
p. 84, pi. xviii., figs. 1-11. 
This species is generally transversely oval and sub-globose, with equally deep 
and uniformly convex valves up to a certain age ; after wldeli a mesial ibid of 
greater or lesser elevation is gradually formed in the dorsal valve, and to which 
corresponds a sinus in the opposite one. The frontal margin is, therefore, 
either nearly straight, or presenting a greater or lesser curve. The beak is 
incurved and truncated by a small cii'cular foramen, which is contiguous to the 
umbone of the dorsal valve. Externally the entire surface is regularly covered 
with numerous concentric scaly ridges, from each of which radiate closely set 
fringes of elongated somewhat flattened spines ; and, indeed, so closely packed 
are the spiny ridges, that in the perfect sheU no portion of the valve could be 
perceived. Specimens are not, however, to be obtained with tlieir spiny invest- 
ment from the hard limestone matrix, but from the decomposing shales exam- 
ples may sometimes be picked up in which portions of the spines are still pre- 
served. The interior arrangements are siinilar to those of the two species 
already described. 
Athyrh Bojimi occurs in the shales of Coalbum and Broekley, near Lesma- 
hago, and at West Broadstone, near Beith. 
SuB-GENTJS Retzia. King. 1850. 
The species which compose this sub-genus are Terebratula-shaped, with a 
perforated, or punctured shell-stracture, and by this character they appear to be 
chiefly cbstinguished from Ailnjrh. Interiorly they possess spiral processes for 
the support of the oral arms, with their extremities directed outwards ; but I 
have never yet succeeded m procuring a specimen whercm the details could be 
satisfactorily developed. I am acquainted with but a single species from the 
Scottish carboniferous strata. 
