DrawUserPrimitives culling parts of mesh

public static RasterizerState MyRasterizerStateCullNoneSolid = new RasterizerState() { FillMode = FillMode.Solid, CullMode = CullMode.None };

public Chunk(int chunkX, int chunkY, int width, int height, int mapWidth, int mapHeight, float[] noiseMap, GraphicsDeviceManager graphics, PlanetTypes planetType) {
 Width = width;
 Height = height;

 ChunkY = chunkY;

 List < Vector3 > positions = new List < Vector3 > ();
 List < Color > colors = new List < Color > ();
 VertexPositionColor[] vertices;

 float pX = chunkX * width * innerRadius * 2;
 float pY = chunkY * height * outerRadius * 3 / 2;

 for (int y = 0; y < height; y++) {
  for (int x = 0; x < width; x++) {
   float tx = pX + (x + y * 0.5 f - y / 2) * (innerRadius * 2 f);
   float ty = pY + y * (outerRadius * 1.5 f);

   float value = noiseMap[(y + chunkY * height) * width * mapWidth + x + chunkX * width];

   int color = (int)(MathHelper.Clamp(value, 0.1 f, 0.9 f) * 255);

   Vector3 pos = new Vector3(tx, ty, value * 100);
   for (int i = 0; i < 6; i++) {
    Vector3 c1 = pos + corners[i];
    Vector3 c2 = pos + corners[i + 1];

    if (i == 0 || i == 4 || i == 5) {
     int ax = y % 2 == 0 ? AdjentsEven[i].Item1 : AdjentsOdd[i].Item1;
     int ay = y % 2 == 0 ? AdjentsEven[i].Item2 : AdjentsOdd[i].Item2;
     int nx = x + ax;
     int ny = y + ay;

     float tx2 = pX + (nx + ny * 0.5 f - ny / 2) * (innerRadius * 2 f);
     float ty2 = pY + ny * (outerRadius * 1.5 f);

     int noiseMapIndex = (ny + chunkY * height) * width * mapWidth + nx + chunkX * width;
     if (noiseMapIndex >= 0 && noiseMapIndex < noiseMap.Length) {
      float value2 = noiseMap[noiseMapIndex];
      int color2 = (int)(MathHelper.Clamp(value2, 0.1 f, 0.9 f) * 255);

      Vector3 pos2 = new Vector3(tx2, ty2, value2 * 100);

      Vector3 c3 = pos2 + corners[(i + 4) % 6];
      Vector3 c4 = pos2 + corners[(i + 3) % 6];

      positions.Add(c1);
      positions.Add(c2);
      positions.Add(c3);

      colors.Add(new Color(color, 125, 125));
      colors.Add(new Color(color, 125, 125));
      colors.Add(new Color(color2, 125, 125));


      positions.Add(c4);
      positions.Add(c3);
      positions.Add(c2);

      colors.Add(new Color(color2, 125, 125));
      colors.Add(new Color(color2, 125, 125));
      colors.Add(new Color(color, 125, 125));
     }

    }

    //if(y >= CHUNK_WIDTH/ 2)
    //{
    //    positions.Add(pos);
    //    positions.Add(c2);
    //    positions.Add(c1);

    //    colors.Add(new Color(color, 125, 125));
    //    colors.Add(new Color(color, 125, 125));
    //    colors.Add(new Color(color, 125, 125));
    //}
    //else
    //{
    positions.Add(c2);

    positions.Add(pos);

    positions.Add(c1);

    colors.Add(new Color(color, 225, 225));
    colors.Add(new Color(color, 225, 225));
    colors.Add(new Color(color, 225, 225));
    //}
   }
  }
 }

 //Vertices = new VertexBuffer(graphics.GraphicsDevice, typeof(VertexPositionColor), positions.Count, BufferUsage.None);

 //positions.Reverse();
 //colors.Reverse();
 Vertices = new VertexPositionColor[positions.Count];

 for (int i = 0; i < positions.Count; i++)
  Vertices[i] = new VertexPositionColor(positions[i], colors[i]);

 BoundingBox = BoundingBox.CreateFromPoints(positions);

 testEffect = new BasicEffect(graphics.GraphicsDevice);
}

public static void LoadContent(ContentManager content) {
 effect = content.Load < Effect > ("Shaders/FogOfWar");
}

public void Draw(SpriteBatch spriteBatch, GraphicsDeviceManager graphics, Camera camera) {
 //if (camera.Frustum.Contains(BoundingBox) == ContainmentType.Disjoint)
 //    return;

 Space.ChunksDrawn++;

 effect.Parameters["WorldViewProjection"].SetValue(camera.ViewMatrix * camera.ProjectionMatrix * Matrix.Identity);


 graphics.GraphicsDevice.RasterizerState = MyRasterizerStateCullNoneSolid;
 graphics.GraphicsDevice.DepthStencilState = DepthStencilState.Default;

 foreach(var pass in effect.CurrentTechnique.Passes) {

  pass.Apply();
  graphics.GraphicsDevice.DrawUserPrimitives < VertexPositionColor > (
   PrimitiveType.TriangleList,
   Vertices,
   0,
   Width * Height * 6, VertexPositionColor.VertexDeclaration);
 }
}