Me eT a ee 
ON THE CLASSIFICATION OF THE LABYRINTHODONTS. 167 
latirostris) ; oval, small, somewhat oblique, distant *, the pointed anterior ends con- 
verging; orbital margin raised. Palatine foramina. Hlongate, large, adjacent, 
pointed in front. External nasal foramina. Elongate-oval, approximated. Teeth 
(disposition). Premaxillary not fewer than 8 on each side in 4. Decheni, or 11 in 
A, latirostris; maxillary not fewer than 30, irregular, of small size, diminishing 
behind ; palato-vomerine, two or three tusks in front of the choana, and 12 or more 
behind, diminishing backwards to size of maxillary teeth; mandibular, a single row 
of nearly uniform ,teeth. Zveth (structure). Conical, finely striate, tipped with a 
two-edged crown of enamel when new and small; the dentine gives off a relatively 
small number of converging folds, which alternate with simple, radiating extensions 
of the pulp-cavity. Mandibular articulation. Somewhat weak ; postarticular pro- 
cess short. Cranval sculptwre. An incomplete lyra, faintly marked ; pitting radiate, 
obscure in young specimens. Thoracic plates. Rhomboidal plate further produced 
in advance of the centre of radiation than behind it, with a slight median ridge ; 
lateral plates triangular, truncated behind, extending backwards a little beyond the 
centre of the median plate; sculpture radiate, rather obscure. Vertebre. Noto- 
chordal ; the superior and inferior arches are ossified, and there are also three osseous 
cortical plates to each vertebree, one ventral and two lateral. Ribs. Short, nearly 
straight, extending throughout the trunk and into the caudal region. Fore limb. 
About half the length of the skull; at least four digits (number uncertain). Hind 
limb. Rather larger than fore limb (as 3: 2 in adult specimens) ; at least four digits. 
Scutes. Oval, lancet-shaped, &c., imbricate; ventral armour forming a chevron 
pattern, which is reversed behind. 
A. Decuent, Goldf. (A. medius, Goldf. ; A. minor, Goldf.). 
Skull nearly twice as long as broad (adult). Orbit elongate-oval. 
Measurements +. in 
Mishel lath yotip allt jis. splat urea sibletavolsye,s) aiphelelewr siaie-pigle: Sayeleerera ee bel, 
Length of skull along middle line .......... 66sec eee eee ee eee 10:9 
Greatest breadth of skull. ............eeeeee Heer bY Moon cir ne 5°62 
renataat AGI e\OL- Obits: 5 cis-cise fe om «niepeln ajebblales > elsfereieiee si) 3575 
From centre of occiput to posterior end of orbit .........+..+-4- 2°55 
From tip of snout to anterior end of orbit........... cece eee e eee 75 
GHENT OLDIpie .% ya olois.vin = piabs, > wpm pipet niniens “lee rel rleasleys as) 1:3 
IECELY ET 0) Ole ORS Ot COC GICOT te ae EO pe ICr ara thre ‘75 
Heast widthoot interorbital Space... s..ccce eter eases daaane 1:25 
Distance between external nasal foramina...... 6. sees eee eeee ‘875 
From tip of snout to external nasal foramen............++ +. eee 1:375 
rentestid ent hl OkmaMNG DION Teor u's t/t 7. o's sere whee aiethe pice = ate 15 
Greatest length of mandibular tusks ......... cece eee cece eee eee ‘48 
Length of median thoracic plate ............eeeees (upwards of) 7 
Greatest width of median thoracic plate .........eee cesses eae 2" 
Length of 8 posterior thoracic vertebree..........5 are u ne gions sary eG 
Locality. Coal-measures of Saarbriick ; Coal-measures of Artinsk, Ural}. 
References. Goldfuss, Beitriige zur vorweltlichen Fauna des Steinkohlengebirges 
[1847].—Burmeister, Die Labyrinthodonten aus dem Saarbriicker Stein- 
kohlengebirge (Archegosaurus) [1850]—Von Meyer, Reptilien aus der 
Steinkohlenformation in Deutschland {1858].—Jordan, ‘‘ Frgiinzende Beo- 
bachtungen zu der Abhandlung von Goldfuss iiber die Gattung Archego- 
saurus,”’ Verh. nat. Vereins d. Preuss. Rheinlande, p. 76, t. iv. fig. 1, t. vi. 
[1849].—Owen, Paleontology, p. 168 [1860].—Kichwald, Lethza Rossica, 
vol. i. pt. ii. p. 1683 [1860]. 
* That is, separated by more than the transverse diameter of one of them. 
+ The measurements of the skull are taken from the nearly perfect example figured by 
Von Meyer (Reptilien aus der Steinkohlenformation, t. 4). The other measurements 
are from large and perfect examples of the individual parts belonging to different 
skeletons. 
¢ Hichwald, loc. cit. The identification rests only upon alimb-bone, and is questionable, 
