diff --git a/src/beast/evolution/tree/YulePriorOneOnXBirthRatePrior.java b/src/beast/evolution/tree/YulePriorOneOnXBirthRatePrior.java
new file mode 100644
index 0000000..dfb2f78
--- /dev/null
+++ b/src/beast/evolution/tree/YulePriorOneOnXBirthRatePrior.java
@@ -0,0 +1,65 @@
+package beast.evolution.tree;
+
+import java.util.List;
+
+import beast.core.Description;
+import beast.evolution.speciation.SpeciesTreeDistribution;
+
+@Description("Yule prior that has a 1/X prior on the birth rate, which is analytically integrated out")
+public class YulePriorOneOnXBirthRatePrior extends SpeciesTreeDistribution {
+
+	   @Override
+	    public void initAndValidate() throws Exception {
+	        super.initAndValidate();
+	        
+	        // make sure that all tips are at the same height,
+	        // otherwise this Yule Model is not appropriate
+	        TreeInterface tree = treeInput.get();
+	        if (tree == null) {
+	            tree = treeIntervalsInput.get().treeInput.get();
+	        }
+	        List<Node> leafs = tree.getExternalNodes();
+	        double height = leafs.get(0).getHeight();
+	        for (Node leaf : leafs) {
+	            if (Math.abs(leaf.getHeight() - height) > 1e-8) {
+	                System.err.println("WARNING: Yule Prior cannot handle dated tips. Use for example a coalescent prior instead.");
+	                break;
+	            }
+	        }
+	    }
+
+	    /**
+	    * The Yule prior (as we use it) is proportional to
+
+	    \lambda^n exp(-\lambda H) 
+
+	    where n is the number of species and H is the sum of heights. Throwing on the 1/lambda prior we can integrate analytically:
+
+	    \int_0^\infty \lambda^n exp(-\lambda H) 1/\lambda d \lambda
+
+	    = ...
+
+	    = (n-1)! / H^n
+	    **/
+	    @Override
+	    public double calculateTreeLogLikelihood(final TreeInterface tree) {
+	    	
+	        final int n = tree.getLeafNodeCount();
+
+	        double H = 0;
+	        final Node[] nodes = tree.getNodesAsArray();
+	        for (int i = n; i < nodes.length; i++) {
+	            assert (!nodes[i].isLeaf());
+		        final double height = nodes[i].getHeight();
+		        H += height;
+	        }
+
+	        logP = Math.log(n-1) - n * Math.log(H);
+	        return logP;
+	    }
+
+	    @Override
+	    public boolean canHandleTipDates() {
+	        return false;
+	    }
+}