402 Woodward— Crustacean Teeth. 
discovery is the more acceptable, because the teeth have never yet 
been met with at Carluke, where the carapaces are found, although 
the Carboniferous beds have been diligently searched for fossils by 
Dr. Rankin for at least thirty years, whilst the localities already 
named as yielding the detached teeth do not furnish remains of the 
carapace. 
The teeth, with one or two exceptions, always occur in ironstone 
nodules, and the best specimens are those which have been ‘ wea- 
thered’ out, as the fossil, being softer than the matrix, cannot readily 
be developed artificially. If exposed too long, being calcareous, they 
become soft, and soon crumble away. 
It is probable that the soft parts of the animal (which contained 
the teeth), having been, after death, detached from the carapace 
whilst undergoing decomposition, became the nucleus for a concre- 
tion of phosphatic matter, which was added to, layer by layer, 
in the same manner as the concretions around organic remains 
in the London Clay, and the ironstone nodules containing leaves and 
Limuli, in the Coal-measures, appear to have been formed. 
Mr. Armstrong informs us that the Dithyrocaris tooth from Campsie 
(Pl. XI. figs. 4 and 4 @) occurs in a bed of black shale, overlying the 
‘Hosie’ Limestone of the Lanarkshire Carboniferous series, which 
is about 670 fathoms below the ‘Ell Coal.’ This is the horizon 
usually taken by the Glasgow geologists in giving the position of 
Carboniferous fossils. No other specimen is recorded from this 
locality. 
Its associated fossils are Nucula gibbosa, N. lineata; Leda longi- 
rostris, L.. attenuata; Nautilus subsulcatus; Goniatites Gilbertsoni, 
G. vesica; a profusion of Spirifera Uru, Orthoceras pygmeum, and 
a large Cythere? 
Those from Orchard Quarry, near Thornliebank, Renfrewshire 
(Pl. XI. figs. 8, 3 a, 36, and 5, 5a), are from a bed of shale about 
300 fathoms below the ‘ Ell Coal.’ The common fossils in this bed 
are several species of Cypricardia, Leda, Orthoceras, Productus cos- 
tatus, Bellerophon Uri, B. Leveilleanus, Macrocheilus, Pleuroto- 
maria monilifera. No trace of carapace has been discovered at 
either of these localities. 
The specimen with the teeth attached to the portion of carapace, 
from East Kilbride (Pl. XI. fig. 6), was found in shale associated with 
Brachiopoda, Corals, &c. The teeth are common at Orchard Quarry, 
but only a single specimen has been met with either at Lickprivick 
or Campsie. 
That these detached fossil remains are the teeth of Crustacea there 
cannot now be the least doubt; for, in addition to the evidence 
afforded by the remains of the allied genus Ceratiocaris (Pl. XI. fig. 1), 
and by the fragment of Dithyrocaris (Pl. XI. fig.6), one needs only to 
compare the gastric teeth of the common Lobster (Homarus vul- 
garis), figured in our plate (fig. 12), with the most perfect tooth of 
Dithyrocaris (figs. 3, 3 6), to see the striking similarity between them, 
both in general form and in minuter details. 
They so strongly resemble the molar teeth of the Vertebrata also, 
