Shapeer

Ages ago I was reading a Celtic mythology book that mentioned a snake with a rams head but said nothing else on the beast, so heres my rip off interpretation!

Shapeer:

These british coastal mammal/reptiles are known (or rather, not) for their shyness. What is known however is that shapeers are long, slender creatures with laterally flattened, paddle-like tails. There is some sexual dimorphism in the species, with the females attaining as much as 20m, 5m more than males. Females also posess far smaller horns, have darker markings and heavier-duty scales, which is thought to be an evolutionary adaption to protect the female's body on the long treks up streams and over land to find a suitable nesting sites. Clutches of as many as 15 very large, leathery shelled, granite-coloured eggs are lain in mossy ground in deciduous forest or in marshy highland areas, well away from saline water wich is know to prove fatal to developing embryos. After a long, cool incubation, the eggs hatch and the large, fully formed neonates stay in the nesting area untill after they shed their skin for the first time. Once the new skin is fully dried and has become impermeable enough to withstand saltwater, they return to the coast, travelling at night and taking them as long as two weeks. Sexual maturity is reached at 50 years of age, when the mane develops. The long, smooth flowing mane remains so untangled in the rough winds and water spray that it is rumoured that mermaids comb it for them. This is yet to be documented.