(>80%). The Eastern green mamba (Dendroaspis angusticeps) has an average venom yield per bite of 80 mg according to Engelmann and Obst (1981). The subcutaneous for this species ranges from 0.40 mg/kg to 3.05 mg/kg depending on different toxicology studies, authority figures and estimates. The mortality rate of untreated bites is unknown but is thought to be very high (70–75%). Generally the calmest and most shy of the green mamba species, the Eastern green will still strike repeatedly if cornered or agitated. The Jameson's mamba (Dendroaspis jamesoni) is known to be quite aggressive and defensive. The average venom yield per bite for this species is 80 mg, but some specimens may yield as much as 120 mg in a single bite. The SC for this species according to Brown (1973) is 1.0 mg/kg, while the IV is 0.8 mg/kg. Envenomation by a Jameson's mamba can be deadly in as little as 30 to 120 minutes after being bitten, if proper medical treatment is not attained. The mortality rate of untreated bites is not exactly known, but it's said to be very high (>80%). True cobras The cobras (Naja spp) are a medically important group of snakes due to the number of bites and fatalities they cause across their geographical range. The genus Naja consists of 20 to 22 species, but has undergone several taxonomic revisions in recent years, so sources vary greatly. They range throughout Africa (including some parts of the Sahara where Naja haje can be found), Southwest Asia, Central Asia, South Asia, East Asia, and Southeast Asia. The most recent revision, listed 28 species after the synonymisation of Boulengerina and Paranaja with Naja. But unlike some other members of the family Elapidae (the species of the genus Bungarus, genus Oxyuranus, genus Pseudohaje, and especially genus Dendroaspis), half of the bites by many species of both African and Asian origin of the genus Naja are "dry bites" (a dry bite is a bite by a venomous snake in which no venom is released). Roughly 45–50% of bites by most cobra species are dry bites and thus don't cause envenomation. Some of the species which are known and documented to deliver dry bites in a majority of cases include: Naja naja, Naja kaouthia, Naja sputatrix, Naja siamensis, Naja haje, Naja annulifera, Naja anchietae and Naja nigricollis. Some species will inject venom in the majority of their bites, but still deliver