BRACHIOPODA. 
85 
Genus SPONDYLOBOLUS, McCoy. 1852. 
1852. /Spondylobolus, McCoy. Annals and Magazine Natural History, vol. viii, p. 407. 
1853. Spondylobolus, Davidson. Introd. Brit. Foss. Brachiopoda, p. 125; pi. ix, figs. 241-243. 
1855. Spondylobolus, McCoy. British Palaeozoic Fossils, p. 255, pi. 1 h, figs. 4, 5. 
Types, Crania Sedgwicki, Lewis, C. craniolaris, McCoy. Lower Llandeilo. 
(The former species is not considered a Brachiopod by Mr. Davidson ; vide 
Silurian Brachiopoda, p. 83, pi. viii, fig. 25.) 
Very little is known of this genus except from the original description given 
by McCoy, and the figures subsequently produced in the “ British Palaeozoic 
Fossils, p. 255, pi. I h, figs. 4, 5. Mr. Davidson, from the first, expressed his 
doubt of its generic value, but he has reproduced the original figures in both 
the places cited. In the latter* he promises a further reference and explana¬ 
tion of the fossil. We have not, however, been able to find anything of later 
date, further than a casual mention of the name,f and even the species does 
not appear in any of his various lists and indexes. 
McCoy’s diagnosis of the genus is as follows: 
“ Subcircular, slightly narrowed towards the indis¬ 
tinct, short hinge-line, nearly equivalve, flattened. 
Small valve with a slightly excentric apex; beneath 
which, on the interior, the substance of the valve is 
thickened into a wide, undefined boss. Opposite valve FIG. 41. Spondylobolus craniolaris 
slightly longer, from the apex being perfectly mar¬ 
ginal and slightly produced, channeled by a narrow, triangular groove below, 
the anterior end of which is flanked by two very prominent thick, conical, 
shelly bosses, representing hinge-teeth; substance of the valve thick, testace¬ 
ous, not glossy, minutely fibrous, but not distinctly punctated under a lens of 
moderate power, except by the ends of these fibres.” 
With our imperfect knowledge of this fossil, little can be said further than 
to suggest its general obolelloid appearance, and the possibility that its cardinal 
bosses may indicate a similar relation between it and Obolella as is found to 
exist between the species of the genus Barroisella and the true Lingulas. 
* Expl. pi. viii, figs. 26, 27. 
t General Summary, 1884. p. 352. 
