This report presents r e s u l t s of a study in Schistocerca gregaria of large dorsal unpaired median neurons found p r e v i o u s 5 in ganglia of several insects (Crossman e t a l . , '71a; Hoyle, unpublished). Most of these neurons give off a single median neurite t h a t makes a T-branch, providing symmetrical l e f t and r i g h t e f f e r e n t axons. These axons emerge i n ganglion nerve trunks and terminate in each of two nerves. They then travel t o major skeletal leg muscles. One of the neurons supplies only the extensor t i b i a e ( j u m p i n g muscle).The f i n a l branches of t h i s neuron parallel the f a s t axon and supply muscle units t h a t receive the f a s t axon only. All the muscle f i b e r s in a unit a r e innervated (multiterminally) by the f a s t axon, b u t only a few receive terminals of the dorsal neuron i n addition. The endings a r e of neurosecretory type, containing large numbers of dense core vesicles. Their function i s unknown.I n 1971, Crossman e t al. ( ' 7 1 a ) reported large nerve cell bodies in the mid-lines of the dorsal surfaces of cockroach and locust thoracic ganglia t h a t give large, overshooting action potentials. Each neuron makes a T-branch, the arms o f which are symmetrical, l e f t and right neurites.forms axons t h a t emerge from ganglion nerve trunks. appear t o be e f f e r e n t neurons supplying muscles, although t h e i r i d e n t i t y could not be ascertained. Each of these branchesThe large dorsal c e l l s thusIn both cockroach and locust, Crossman e t a l . ( ' 7 2 ) consistently found eight o f these neurons, apparently a l l identical and with similar branching patterns.In t h e i r f i r s t detailed account Crossman e t a l . ( ' 7 l a ) , showed the neuron as having b u t a single pair of o u t p u t s , in N5 (designation of Pringle, '39). In a 159