Bring clam juice to boil in medium saucepan. Add shrimp; reduce heat to medium, cover and cook just until shrimp are opaque in center, about 2 minutes. Using slotted spoon, transfer shrimp to cutting board; cool. Coarsely chop shrimp.
Mix sliced green onions, mayonnaise, lemon juice, paprika, and cayenne in medium bowl. Mix in shrimp and
crabmeat. Season with salt and pepper. (Can be prepared 6 hours ahead. Cover and chill.)
Preheat oven to 375°F. Brush both sides of baguette slices lightly with oil; arrange in single layer on baking sheet. Bake until bread is golden, about 10 minutes. Cool.
Mound shrimp mixture atop bread. Place on platter and serve.
