Although admission to the two highest "ordines" (orders), i. e. Admission to the higher "ordines" brought distinction and privileges, but also a number of responsibilities. The two highest "ordines" in Rome were the senatorial and equestrian. Secundum Classes, Ordines, Genera, Species. The four extensive treatments which Young classified as "ordines Rachelis" differ considerably. Imperfect ordines are mostly theoretical and rare in practice, where perfect ordines predominate . There are about 50 recognized Ordines Romani (singular&colon; Ordo Romanus). By contrast his "ordines naturales" numbered 69, from Piperitae to Vagae.