162 REPORT—1874. 
From centre of occiput to posterior end of orbit .......eeee sees 16 
From tip of snout to anterior end of orbit........ 2... e eee eens 1-25 
TienethtOmarpibtas's «ales wallets tsk sec stemimatcrte eile fl. \e cattle oo Fae aS 
WWiadtbitchorbitire stasis cane ws aia thsla se awe wee ss 6 ove abe lelatenenaete 6 
Least width of interorbital space ......-...0sseccevsreacsnnes “45 
From tip of snout to external nasal foramen ....... fe 375 
B, AUSTRALIS, Huxley. 
Locality. Triassic (?) rocks of some part of Australia. Precise locality unknown. 
References. Huxley, Quart. Journ. Geol. Soc. vol. xv. p. 647, pl. xxii. figs. 1, 2 
[1859]. 
III. CHAULIODONTA. 
Loxomma, Huxley. 
Skull (figure). An elongated isosceles triangle, with large rounded postero-lateral 
expansions and short epiotic cornua; coronal tract elevated, bounded on each side 
by temporal depressions; auditory openings indenting considerably the upper 
surface. Orbits. Very large, irregular-oval, with cusps proceeding from the 
posterior part of both inner and outer margins; narrowed in front; slightly 
oblique, the long axes diverging forwards ; edges raised ; interorbital space less than 
the transverse diameter of the orbit. External nasal foramina, Oval, lateral, 
distant *. Choane. Marginal, distant, small, slightly posterior to the external nasal 
foramina. Teeth (disposition), Premaxillary, three or four on each side, larger than 
maxillary; maxillary numerous, subequal ; palato-vomerine, large tusks before and 
behind the choane ; mandibular very unequal, 18 to 25. Teeth (strngiuney: Coni- 
cal, striate, with opposite (anterior and posterior) cutting-edges; a thin layer of 
enamel invests the crown of the tooth, and descends low down upon the sides ; the 
dentine forms a thick and compact internal lining to the cap of enamel in the upper 
half of the tooth, occupying nearly all the space, and reducing the pulp-cavity to a 
small flattened cylinder in the centre of the tooth; in the lower half of the tooth 
the pulp-cavity expands and the parietes become somewhat thinner; at the same 
point the dentine separates into numerous vertical lamellz, or folds, and a LS laced 
layer of dentine appears ; towards the base of the tooth the pulp-cavity is large, 
occupying about one third of the diameter; the dentinal lamellae are numerous, 
irregular, rarely branched, and radiately disposed around the pulp-cavity; the peri- 
pheral layer of dentine occupies the outside of the tooth, and takes a sinuous course 
along the centre of each lamella; when seen in cross section, each turn of the 
sinuous lamella of peripheral dentine appears to be strengthened by a short out- 
standing process, so that the lamella itself appears to be angulated ; dentinal tubules 
pass from the peripheral layer at right angles. Mandibular articulation. Shallow, 
transversely elongated ; postarticular process wanting. Cranial sculpture. A honey- 
comb pitting covers the chief part of the skull: there is a lyra consisting of two 
grooves which occupy the summits of slightly elevated ridges in the preorbital 
tract; the grooves begin in the interorbital space, and pass forwards, diverging 
regularly, to the maxillo-premaxillary suture ; they are connected in front by a 
transverse groove: short maxillary grooves; no malar grooves. Thoracic plates 
have been described as those of Loromma, but without satisfactory identification. 
Vertebre. Centra well ossified, biconcave ; spinous processes broad and lofty. 
Ribs. Long, slightly curved, strong. 
* Tn the restoration of the skull of Loxomma given in last year’s Report (t. i.) the ex- 
ternal nares are incorrectly placed. They are shown by Mr. Atthey’s fine specimen, 
figured in the paper referred to below, to be external to the mucous grooves upon the pre- 
maxilla. The same paper will enable us to rectify and complete the delineation of the 
sutures upon the upper surface of the skull in this genus. Wecannot accept Messrs. Em- 
bleton and Atthey’s interpretation of the palate of Loxomma, which is founded upon an 
analogy with Crocodilia which we believe to be mistaken. The “palate-plates of the 
maxillaries” are true palatals, and no ectopterygoid exists in the Labyrinthodont skull. 
The apertures named by them ‘posterior nares” are probably vascular canals, and we 
regard the foramina marked ‘“‘ 4p” in t. y. as the true choane. 
