This was done after I was thinking about all the different cock types I drew; although this doesn't show all of the different types I've drawn, it does show a good sampling (I might hafta draw a part II to cover the rest :).  From left to right, top to bottom, it's:  deer, with regular, no sheathed cock; horse, with equine dick; water dragon, with ribbed dick; fox, with canine knot-in-the-base dick; and lion, with slightly-attached penis sheath.