tectiform

from The Century Dictionary.

• Like a roof in form or use; covering, or forming a cover; lid-like; specifically, in entomology, ridged in the middle and sloping down on each side: as, the tectiform elytra of some homopterous insects.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective biology, anthropology Roof-shaped; sloping downwards on two sides from a raised central ridge.
• noun anthropology A type of cave-painting or engraving in the shape of an upward-pointing wedge or arrow.