Sentence:  Laurence M . Klauber put length at maturity at two thirds the ultimate length for <WSD>some</WSD> rattlesnakes , and Charles C . Carpenter 's data on Michigan garter and ribbon snakes ( Thamnophis ) show that the smallest gravid females are more than half as long as the biggest adults . 
Meaning of the word marked with <WSD> tags:  quantifier; used with either mass nouns or plural count nouns to indicate an unspecified number or quantity