Alot of animals has a penile bone, so I don't know if can compare different animals that easily.
Look up oosik.
Re: the snake info.
Longest coital session
As in all other matters sexual there is immense variation throughout the animal kingdom in the actual duration of the coital act. In fact intercourse can range from a few seconds to many hours. Copulating snakes typically remain in union for one or two hours or for much longer periods - there is a suggestion that six to twelve hours is average. The record is held by a pair of rattlesnakes who remained in copulatory connection for no less than 22¾ hours. Such long periods may in part be explained by the difficulty the male has, on account of his spiked penis, in getting away! The fluke, Schistosoma heamatobium - with the female eternally living within a fissure in the male's body-has been said to exist in a state of "permanent copulation."
Most remarkable coital mechanics
We have already noted some rather surprising preliminaries or accompaniments to insect coitus, but the mechanics of the coital act itself is sometimes equally remarkable. In bed bug copulation the sperm is placed in a pocket in the cuticle on the ventral surface of the female abdomen, whereupon the sperm actually makes its way through the body wall and reaches the ovaries via the blood stream. In many species - some bed bugs (as well as leeches, planarians, etc.) - the penis actually penetrates the body wall, resulting in a form of hypodermic insemination.