The Prior and Murray-Prior coat of arms
Families with the status of gentry and above, were entitled to their own coat of arms.1) The photo far left is a faded painting of the Prior crest.2)
The next is a drawing of the Prior crest with an explanation3)
This drawing of the crest is by TLM-P.4) 
It appears that TLM-P had tried to find out what the Prior coat of arms were, and got it slightly wrong. On 23 November 1885, he wrote about the crest in his Family Bible 5) Part of what he wrote is hard to read now, but appears to describe his crest as he drew it: that the family arms are ‘Sa. on a bend arm, three chevronels gn. between stars of eight point wavy’. Motto: Malo mori quam foedari. Seat: Rathdowney, Queens County. This all was part of his determination to assert his family's gentry status and despite the family no longer owning Rathdowney.
TLM-P achieved confirmation of his family's gentry status in October 1888 when, as described in Burke's entry 'Prior of Netherfield' in his Landed Gentry book, TLM-P 'obtained confirmation of Arms from the Ulster King of Arms 1888 - Quarterly 1 and 4, vert on a bend ermine three chevronels gules (PRIOR); 2 and 3 per fess gules and or four mullets countercharged (MURRAY).' You really have to be into heraldry to understand - though a copy can be see here: Grant of arms. Or you can look at the following photo of a section of the parchment scroll sent to TLM-P and which confirmed the M-P coat of arms. As seen, it retained the Prior motto, translated as 'death before dishonour'. The first photo below is of the parchment scroll acquired by TLM-P; the second is a close-up of the M-P coat of arms.6)
Another depiction of family arms in one of TLM-P's family bible.7)
Another version of the coat of arms appears in Charles Low, A Roll of Australian Arms, Corporate and Personal:Borne by Lawful Authority
Rigby, 1971, p.145-46, although it is hard to argue that any but the scroll sent by the Ulster King of Arms is the correct version.
Part of crest used in M-P's signet rings.8)