To hear for their tiny hearties

There are many suggestions in this chapter and elsewhere in FW that HCE's sleep / death / internment is also an incubation in the womb of ALP as an egg (Humpty Dumpty) in "foetal sleep" awaiting (re)birth / resurrection. Such a reading of this paragraph suggests ALP moves in "arundgirond in a waveney lyne" - circulating like a line of blood, like "Santa Claus" (dressed in red and bringing "birthday" presents - of oxygen and nutrition), "encircling" (like a womb) her children Isolabella, "then running" (like blood) to the twins "Romas and Reims".

Words here like "spatters" also suggest blood.

"Christmas" also refers of course to the birth of Christ.

Their birth is described as: "the spoiled she fleetly laid at our door" (where her "spoiled" suggests spoilt children; "laid" suggests the laying of eggs; and "our door" to this world is her vagina).