I don't know much about this place at all...evidently it is (or was) located in Plumsted Township, in Ocean County, somewhere New Egypt. It is listed on the 1860 Federal Census, which you can find here.

Another researcher mentioned to me recently though that several of the family names listed on that census are also known to be residents of Ellisdale, so there may be a relation between these place; they could even be the same place for all I know.

A recent visitor had this to say regarding Shelltown:
"Shelltown, no longer exists, today it is what is noted on the map as Ellisdale, which is outside of Allentown, in central NJ. Up until the late 1950's there was a general store/gas station, and a small number of houses and farms. Today there are a few more homes and the Methodist Church that bears the Ellisdale. The church was established in the mid 1800's. The old folks in the town always said that it was called Shelltown because of the large number seashells that were found when the farmers turned over their fields in the spring. "

If you have any information regarding this place, please send me an e-mail.