Spined: Ratmen at Sacrifice (all 3 types - sometimes I go for the rat mages in the one spawn point in the mine), Lizardmen in Despise, or (if I need also need Bones for a BOD) Giant serpents either in Trammel Destard, or the various Treasure Map Islands that spawn them in Fel (as THB Guildmaster, one of my houses has all the runes, and people usually avoid those map spots like the plague on both facets, because of the serpents, and the relatively small size of the islands). The Alligators also give spined on those islands, so filling a beetle can be done rather quickly (stack the leather, then load the beetle only when you get enough to fully load you and it). The down side appears that the islands have their serpent spawn come to a near stop after you kill enough for 1200-1500 leather, which means you got to rotate to a different island between loads (there are 5 islands that are good for it - Amoeba, Valor, Bald, Temple and Skull; 7 if you count Serpent's Hold and North Jhelom, but they have hostile PK residents on some shards).
Horned: Most often, the wyvern by the T2A lighthouse in Trammel (typically the only creature in the area and a near-instant respawn). However, eventually it will spawn over the water, and you either have to place a boat or kill it at range. Other areas include Trammel Destard (the area between the Serpents and the ramp to the Shadow Wyrm level spawns several drakes and wyverns, as does the area behind the bad air), and going out fishing. Lastly, a necro can farm horned quite well at the Ki-rin Passage off of Elemental canyon, killing the Ki-rin next to the poison ele room. You can also go to a different part of the passage to farm the nightmare for barbed.
I typically farm normal leather in the Blighted Grove, honoring and killing Thrasher to raise honor (it gives almost as much leather as a lesser hiryu, with better fame/karma/honor gains and a chance for a ML Minor Artifact drop). A swordsman with a good dragon or reptile slayer can drop Lesser Hiryus in Tokuno in 2-3 hits (especially using armor ignore specials - the Dragon's End 10th anniversary artifact sword is devastating against them in this manner).
