Sentence:  For four of the six ( the anaconda and the amethystine python cannot be included for <WSD>lack</WSD> of data ) there is also a correlation between size at maturity and maximum length , the boa constrictor being the smallest and the Indian python the next in size at the former stage . 
Meaning of the word marked with <WSD> tags:  the state of needing something that is absent or unavailable