...Put some hairs next to the slit and added the connections to the front legs.

Further refining.

Using (render able) spleens to block in the legs.

Converting the spleens to poly and shaping them into the desired form.

In top view I’ve created the wings, starting with a single plane and using the edge extrude method.

I wanted to model those veins. So I had to change the topology with a lot of cutting + welding.