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Two main types of models have been suggested to explain the long durationsand multiple peaks of Gamma-Ray Bursts (GRBs). In one, there is a very quickrelease of energy at a central site resulting in a single relativistic shellthat produces peaks in the time history through its interactions with theambient material. In the other, the central site sporadically releases energyover hundreds of seconds forming a peak with each burst of energy. We presentthree kinematic arguments against a single relativistic shell. These argumentsare based only on symmetry. We show that the average envelope of emission ofGRBs is a linear function rather than the power law expected for a singlerelativistic shell. We show that presence of gaps in GRBs is the strongestargument against a single relativistic shell. We estimate that the fraction ofa single shell that can produce gamma-rays in a GRB with multiple peaks isabout 0.001, implying that single relativistic shells require 1000 times moreenergy than previously thought. We conclude that either the central site of aGRB must produce 10^{51} erg/s for hundreds of seconds, or the relativisticshell must have structure on a scales the order of sqrt(epsilon)/Gamma, whereGamma is the bulk Lorentz factor and epsilon is the efficiency.Comment: 5 pages, latex, to appear in Gamma-Ray Bursts, 4-th Huntsville  Symposium, eds Meegan, Preece, Koshu

Kinematic arguments against single relativistic shell models for GRBs