I found this on the greek page... it's not like these girls didn't read this and KNOW what the Adelphean Society was.
Sorority History Nationally
The first society for women, the Adelphean Society (now Alpha Delta Pi) was established in 1851 at Wesleyan College in Macon, Georgia. The Philomathean Society (later named Phi Mu)[14] was founded at Wesleyan College a year later in 1852. The Adelphean Society and the Philomathean Society did not take on their modern Greek names (Alpha Delta Pi and Phi Mu, respectively) until 1904 when they expanded beyond the Wesleyan campus. They are now often referred to as the Macon Magnolias. Many aspects of Alpha Delta Pi and Phi Mu (such as the stars and hands on their badges and the mascot of the lion) are similar due to the fact that while at Wesleyan a founder of Alpha Delta Pi and Phi Mu's Mary Ann DuPont (Lines) were roommates.
On April 28, 1867, Intercollegiate Sorosis (later known by its original Greek motto Pi Beta Phi) was founded at Monmouth College, in Monmouth, Illinois. It is the first sorority founded on the model of the men's fraternity. A year later it established a second chapter at Iowa Wesleyan College.
In the mid-1800s women were beginning to be admitted to previously all-male universities, and there were many women who felt that it was in their best interest to band together. The first collegiate women formed women's fraternities in an effort to counteract the widespread opposition to their presence. [15]
The earliest organizations were founded as "women's fraternities" or "fraternities for women;" the term sorority was coined by professor Frank Smalley in 1874, in reference to the Greek organization being established at Syracuse University, Gamma Phi Beta. Alpha Phi was also established at Syracuse University, in 1872, and along with Alpha Gamma Delta, these three sororities make up the Syracuse Triad. The first organization to adopt the word sorority was Sigma Kappa, established on November 9, 1874 at Colby College in Waterville, Maine.
http://studentaffairs.utep.edu/Default.aspx?tabid=55990