Baena antiqua, Lambe 1902, Lambe, 1902

Lambe L. M., 1902, New genera and species from the Belly River Series (mid-Cretaceous), Geological Survey of Canada Contributions to Canadian Palaeontology 3, pp. 25-81 : 44-45

Baëna antiqua . Sp. nov.

Part of the carapace of an apparently uu described species of Ba'ena was obtained from Red Deer river, below Berry creek, in 1901. Near it was found the anterior end of a plastron that, judging from the surface markings, thickness of the shell, general appearance and size, evidently belongs to the same species and probably to the same individual.

What is preserved of the carapace ( figure 10 , A) is in an excellent state of preservation. Five neurals in all are represented with five pairs of costals. The sutures are sinuous and fine but can be traced with ease. The sulci are very distinct.

The neurals are rather irregular in shape and of nearly equal size. The costals partake of the same irregularity of outline. The outer surface is almost smooth, the only unevenness being due to a few striations and depressed, roughened markings erratically disposed. Striationsalso occtir at right angles to the sutures, forming an obscure border sculpture. The vertebral shields are broader than long, more especially the first one. The rib-heads are well developed. There is a strong and abrupt thickening iu the axillary region but elsewhere the shell is thin. The anterior border is evenly- rounded.

The front end of the plastron ( figs. 10 , B and 0) is rather broad in proportion to the length of its component parts of which the epiplastrals, the entoplastral and small portions of the hyoplastrals are preserved. The entoplastral, seen from below is diamond shaped, a little broader than long, and placed far forward on account of the shortness of the suture between the epiplastrals in front. Seen from above, or within, the entoplastral is much longer than broad, its breadth being reduced and its posterior half prolonged backward. Similar extensions of the posterior border also occur in the upper surface of the epiplastrals. Sulci, as indicated in the figure, define the boundaries of thegular and intergular shields.

Other fragments, in the collection, may help to further elucidate the structure of the shell of this species.

Belly Eiver series; below the mouth of Berry creek. Red Deer river, 1901.

Measurements.
	M.
Extreme length of specimen, on median line	186
Estimated length of carapace	290
Length of 1st neural	033
Breadth of same	027
Length of 2nd neural	030
3rd "	-037
" 4th "	032
5th "	-031
Length of 3rd vertebral shield.,	065
Extreme breadth of same	075
Breadth of entoplastral, lower surface	027
Length of same	022
Thickness near front margin of carapace	007
" " plastron	0065
Thickness of 2nd costal at proximal end	-005
' " distal end	-004
Maximum thickness in axillary region	026

Belly River series, Red Deer river, 1901.

Figures

FiG. 10. Baena antiqua; A, part of the carapace; B, lower surface of anterior lobe of plastron; C, upper or inner surface of anterior lobe of plastron. One-haLf the natural size. The sinuous lines indicate the sutures between the bones, the heavy ones the boundaries of the epidermal shields. The letters are as in preceding figures.

Fig. 3. Carapace of Trionyx vagansi, from Red Deer; a, out line of the traverse curve of its upper surface. One-eighth the natural size. Letters as in figure 1, page 34.