The following is a record I have looked at, but I do not believe it is the same Peter Connell I am interested in.
For one thing, Peter arrived in the US on June 26, 1847, and the record below is closer to Peter's birthdate in the early 1800s.
I will not discount Canadian records, because Peter was a sailor in about 1855 and many Irish reached the US through Canada.
Canadian Immigrant Records, Part Two Surname Connell Given Name Peter Marital Status 10 family members Year of Record 1825 Comments Group #270 Source/Event A List of Persons who gave their names to Richard O. A. Aldworth Esqr. Newmarket being desirous to emigrate to Upper Canada. Total of 31 Families; 3656 Individuals. Dated 12th May 1825. P. Robinson. Reference Transcribed from (film of) original documents held in the collection of the National Archives of Canada [Ottawa]: MG 11, Colonial Office 384, vol. 13, page 180, reel B-885.