Observations on the vertebral hypapophyses and associated Musculature in some snakes, with special reference to the Colubridae

Hypapophyses are reported to be present on the anterior precaudal vertebrae of representatives of all snake families, except the Typhlopidae, Leptotyphlopidae, and Uropeltidae. The processes occur on all precaudal vertebrae in the Acrochordidae, Colubridae (auct.), Elapidae, Viperidae, and two subfamilies of the Boidae, the Bolyerinae and Tropidophinae. Among the numerous genera of the Colubridae caudal extent of the presence of the hypapophyses is variable, even within a genus or species.\nCope (1864) associated hypapophyses on the posterior precaudal vertebrae with the Homalopsinae. In the years following he utilized the character to distinguish the Homalopsinae (1886), the Colubrinae (1887), the Natricidae (1893); in his last classification (1900), Cope divided the families Colubridae and Dipsadidae into two informal series of genera based on the presence or absence of hypapophyses on the posterior precaudal vertebrae.\nBoulenger (1893-96) used the presence or absence of posterior hypapophyses in a similar manner to separate the genera of two subfamilies of the Colubridae, the Colubrinae and Dipsadomorphinae. Several authors since have used the character in organizations of the confusing array of colubrid genera (Dunn, 1928; Bogert, 1940; Smith, 1943, who suggested the terms Hypophysia and Anhypophysia for the two basic types; Underwood, 1967). Malnate (1960) suggested a possible evolutionary sequence for the character in the Colubridae. Auffenberg (1963) recommended that more detailed observations be made of the hypapophyses.\nRosén (1905a, b) took exception to Boulenger's statements regarding posterior hypapophyses in some genera. Brongersma (1938) reviewed Rosen's work, confirmed his findings, and added that hypapophyses are