ON THE CLASSIFICATION OF THE LABYRINTHODONTS. 159 
alveolar margins.” —Hualey. Cranial sculpture. Pitted, with the intervening ridges 
rising at intervals into slender truncated prominences; obscure traces of a lyra. 
Measurements (from Prof. Huxley’s Memoir and figures). 
Length of skull along middle line ....... 2... ..ccec esses eeeee 10 
Gieeieet brent th OSM, 1b... oar sinlccewadsvetsespncaces 4 
Biemath af muddiGiOr OFDIts. .. 6 is cus yenescvvevinacece's (about) 7:5 
From centre of occiput to posterior end of orbit ..............05 2:25 
From tip of snout to anterior end of orbit. .... 0.0... cece eee eae 75 
Bene thot Orbit. oe. ee HELA ae canes a LEON Ue Aias cs AR «, SONY 75 
SE CEOM ON WED sc Uicte waters vg.’ wo ois niches mNBMabIcl me welh, glia se oiws ‘75 
Least width of interorbital space.......... cscs eeeeeeeceeceees 2-4 
Distance between external nasal foramina............ eee eee ees 2:25 
From tip of snout to external nasal foramen............0.e ee eee 3°25 
Least distance between palatine foramina................00000% 2°8 
Average length of saucillary ENO ie dd Aookudan cones tbe (about) +25 
D. Bucxuannt, Lloyd. 
Locality. Permian Sandstone of Kenilworth. 
Reference. Huxley, Appendix to Howell’s Memoir on the Warwickshire Coal- 
field &c., Mem. Geol. Surv. [1859]. 
As to the age of the rocks in which Dasyceps occurs, see Howell, ibid. p. 32, and 
Ramsay, Quart. Journ. Geol. Soc. vol. xi. p. 198. 
Anthracosaurus, Huxley. 
Skull (figure). Triangular, with rounded anterior end, back part not known; the 
upper surface is flat, with a median ridge in the anterior part. Palatine foramina. 
The separate existence of these foramina is doubtful. Choane. Circular, distant. 
Teeth (disposition). The premaxillary and maxillary teeth form a somewhat irre- 
gular series, the teeth being very unequal in size and relatively few in number; 
there is an internal row of vomerine and palatine teeth, including large tusks in 
front, and diminishing in size somewhat irregularly behind; mandibular teeth un- 
equal. Teeth (structure). Conical, pointed, laterally compressed and recurved 
towards the apex, somewhat angular at the base. “Transparent transverse sections 
of the teeth exhibit a singularly beautiful and complex structure. The relatively 
small pulp-cavity sends off primary radiating prolongations, which pass straight to 
the circumference of the tooth, and at a small distance from it terminate by dividing 
usually into two short branches, each of which gives off from its extremity a wedge- 
shaped pencil of coarse dentinal tubuli. These spread out from one another, and 
terminate in a structureless or granular layer, which forms the peripheral portion of 
the dentine, and, from the small irregular cavities scattered here and there through 
its substance, reminds one of the ‘globular dentine’ of the human tooth, An 
extension of this peripheral layer is continued towards the centre of the tooth, 
between every pair of primary prolongations of the pulp-cavity. The short 
secondary processes which are sent out from opposite sides of the primary prolonga- 
tions of the pulp-cavity give off in the same way, from their ends, pencils of con- 
spicuous dentinal tubuli, the ends-of which terminate in the inward extensions of 
the peripheral layer. The secondary processes of adjacent primary prolongations 
alternate and, as it were, interlock with one another, so that the inward extension 
of the peripheral layer takes a sinuous course between them. A thin layer of dense 
and glassy enamel invests the tooth continuously, but sends no processes into its 
interior ; and, of course, under these circumstances there can be no cement in the 
interior of the tooth, nor can its surface be said to be plaited or folded. It will be 
understood that this description gives merely the principle of arrangement of the 
parts of the tooth; its details could only be made intelligible by elaborate figures’”’*. 
Mandibular articulation. Strong, transversely elongated; a well-developed post- 
articular process and an internal buttress are present. Vertebre and ribs. There is 
* Huxley, doc. cit. 
