Draco Aegypticus

A monster that was roaming across Long Island Sound during the events of the story. It was killed by Aetna and the members of the Hephaestus cabin before it came anywhere near Camp Half-Blood. It is mentioned by Chiron when Conrad first arrives at camp. The two of them hear and explosion and see smoke coming up from the horizon. Chiron believes that Aetna and the Hephaestus cabin had "finally found that pesky Draco Aegypticus that was roaming around." When the Hephaestus kids came back the next day, they told stories about their quest and explained that Aetna triggered a volcanic eruption right under the dragon's feet a practically melted it.

Appearance
All that is known about the Draco Aegypticus is that it is very large and ill-tempered. It can also breath fire out of its nostrils. It is apparently armoured everywhere, even its wings, except for its underbelly. This was why Aetna could kill it by triggering a volcanic eruption under its body.

Conrad Fisher and the Primordials: The Land of Serpents
The Draco Aegypticus was seen roaming around the island and the Hephaestus Cabin was sent on a quest to slay it. Somtime during the quest they encountered Aetna, the volcano nymph. She guided them to the monster and a fight broke out between them. Several cabin members were injured by the dragon's firebreath, though Aetna managed to kill it by causing a volcanic eruption beneath the dragon's feet so that it hit its soft underbelly and melted it.