puurvapadalopa-samaasa??

[jonathan.silk at wmich.edu]

In the Pali Jaataka i.303, top, we find the word ratanasaasane.  The English
translators, of course without note, take this as teaching of the 3 jewels. 
My questions: 1) Is there such a thing as *puurvapadalopasamaasa??  I know
about, and know of references to, madhyamapadalopa-s, but nothing with
puurva-.  I am assuming, of course, that it is ti- (= tri) which is being
elided.  2)  Are there any other examples of this usage in Pali or similar
uses in Skt?

Any hints in any direction most happily accepted.

Jonathan Silk