This small pocket knife was listed in the 1940s Elsener/Victoria catalogue. It was known as 50CT: 50 = the Student config (75mm, two blades), CT = Celluloid Tortoise.
I’m putting this under cellidor although this knife predates the cellidor scaled SAKs. Old celluloid has the tendency to decay and shrink. These tortoise celluloid scales however look fine, except for some damage on the front.
Based on the tang stamp (obverse: crossbow; reverse: VICTORINOX) this knife was made between 1923 and 1930.