You have the gist of the first part, but it is Eight acres, not 18. Some words were omitted and others misread, so I found it easier to start again, and I've added the final section for you.
It's usually best to keep to the same lines in your transcription as in the original - makes it easier to find your place if you need to go back.
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[marginated] No. 49 Hurst & an(othe)r to Porter
Reg(istere)d 12th Oct(obe)r 1838 at 10 m(inute)s before one OC(loc)k
To the Register appointed by Act of Parliament for Registering Deeds & so forth.
A Memorial of an Indented Deed of Assignment bearing date the sixteenth day of
Nov(embe)r one thousand Eight Hundred & Thirty Six & made between William Hurst & George Hurst
both of Tullyrain in the Co. of Fermanagh Farmers of the one part & Robert Porter of Derry
in the Co. of Tyrone Farmer of the other part Whereby after Reciting as therein is recited the
s(ai)d W(illia)m Hurst and George Hurst for the cons(iderati)ons therein Granted & Released unto the s(ai)d Robert
Porter All that & those that part of the Lands of Tullyrain known as & for W(illia)m Hursts part
of s(ai)d Lands & as then or lately held & enjoyed by s(ai)d W(illia)m Hurst containing ab(ou)t Eight acres or
thereabouts together with all the Houses or app(urtenance)s thereunto belonging, situate in the parish
of Magheracross Barony of Tyrkennedy & Co of Fermanagh To hold unto the s(ai)d Rob(er)t Porter
his Heirs and Assigns for Ever subject to a proportion of the Rents and Cov(enan)ts in the original Lease
& which Ind(entu)re contained sev(era)l other Cov(enan)ts & was Witnessed as to the executions thereof by
all the parties thereto by W(illia)m Porter of Derry & John Porter of Drigh both in the Co. of Tyrone
and Margret Hurst wife of W(illia)m Hurst of Tullyrain in the Co. Fermanagh Farmer & this Me-
morial as to the Execution thereof by the s(ai)d Rob(er)t Porter is Witnessed by the s(ai)d John Porter
and John Collum of Enniskillen in the Co. of Fermanagh Att(orn)ey at Law. Robert X Porter <his mark>
(Seal) Signed & sealed & delivered in the presence of John Collum John Porter. The above
named John Porter of Dreigh in the Co. of Tyrone Farmer maketh oath & saith that he
is a Subscrib(er) & Witness to the Deed of which the above Writing is a Mem(oria)l & also to the above
Mem(oria)l & saith he was present & saw the s(ai)d Deed duly executed by all the parties thereto and
this Memorial by the s(ai)d Rob(er)t Porter & saith the name John Porter subscribed as a Witness
to s(ai)d Deed & Mem(orial) resp(ective)ly is this Dep(onen)ts proper name & Handwriting. John Porter. Sworn
before me at Enniskillen in the County of Fermanagh this 10th day of Oct(obe)r 1838 by virtue
of a Comm(issio)n to me directed out of Her Majesty’s High Court of Chancery in Ireland for
the Kings aff(idavi)ts[?] for s(ai)d Court in s(ai)d Co. & I know Dep(onen)t. Hugh Collum Com(missione)r
Seven Sheets a true Copy [signature]
