As is the case with the cranial muscles (see Chapters 3-7), the most comprehensive comparative analyses of osteichthyan pectoral muscles and pectoral fi n/forelimb muscles of vertebrates that were actually based on a direct observation of taxa as varied as, e.g., the Teleostei, Halecomorphi, Ginglymodi, Chondrostei, Cladistia, Dipnoi, Amphibia and Amniotes, and not mainly on a recompilation from the literature, were provided long ago, by authors Humphry (1872ab), Brooks (1886-1889), Ribbing (1907), Romer (1922-1944), Howell (1933-1937), Haines (1939-1958), and Straus (1942), among others. Thus, despite the quality of these works, their authors could not access information now available concerning, for example, the pectoral and pectoral fi n musculature of Latimeria chalumnae and the essential role of neural crest cells in the development and patterning of the cephalic (see Chapters 3-7) and also the pectoral and pectoral fi n/pectoral limb muscles (e.g., McGonnell 2001) of vertebrates. Also, some of hypotheses proposed in those works regarding the homologies and evolution of osteichthyan pectoral muscles were based on phylogenetic hypotheses that have been contradicted by numerous studies. For instance, Romer (1944) defended that the cladistian Polypterus is more closely related to tetrapods than are the extant dipnoans, a view to which very few authors would adhere nowadays (see Chapters 1 and 2, and also Chapter 9). Chapter 8 provides an updated discussion on the homologies and evolution of the pectoral and pectoral fi n muscles of actinopterygian and sarcopterygian fi shes; the pectoral and forelimb muscles of tetrapods are discussed in Chapters 9 and 10.