Externally it looks very close to Beddome's Cat Snake (B. beddomei) and Collard Cat Snake (B. nuchalis) and usually indistinguishable from these two which are sympatric to it in Western Ghats. Morphologically all three species are known for brown or yellowish dorsal marked with blackish markings. B. ceylonensis can be identified by checking 19 mid body rows, comparatively lower number of ventrals (215-235) and subcaudals (95-108).
Average length- 90cm.
Maximum length- 132cm.
Laterally flattened long body. Scales smooth, long shaped and obliquely arranged. Top dosral scales along the vertebra larger than side scales and of hexagonal shape. Dorsal color brown, yellowish or brown mixed with reddish. Black, dark brown or reddish patches or cross lines found from head to tail. These markings are broadest on vertebral region.
Belly color white, yellow or yellowish-brown; usually with blackish or dark brown patches on the outer edge of ventral scales. Subcaudal scales paired in zig-zag manner.
Head triangular with rounded edge; clearly broader than neck. Top of the head of similar to dorsal color. One black streak runs behind the eye to end of the head. Large eyes with vertical pupil.
Long and thin tail typically like other arboreal snakes with pointed tip. Dorsal body patterns continue to tail in faint form.