So this is in a number of ways an improvement from before, so you're heading in the right direction, but there are definitely still issues that stand out.

First and foremost, it's worth pointing out that you ignored at least one of the restrictions I set for your revisions:

Don't include any contour lines that run along the surface of a single form. I noticed you adding these to your additional masses a lot. With additional masses, we want to focus most of all on how their silhouettes wrap around the structure beneath them. You are still encouraged to include the kind of contour line that defines a relationship between multiple forms (like intersection lines, the kind that we use as part of the sausage method at the joints between sausages).

You used plenty of these, on basically all of your additional forms. For example if we look at this bear, each additional form has been given contour lines to help make them feel 3D on an individual basis, but while some of them have had an amount of thought put towards how they wrap around the underlying structure, several others (like the two top ones on the bear's back) are just plopped on there with no real integration to the rest of the construction.

There are also serious concerns regarding accuracy as well. Struggling with proportion is totally normal, but the positioning of the legs of your animals don't actually correspond entirely with the reference. Looking at the same polar bear, its front arm in your drawing is reaching forwards, whereas in the reference it's positioned further back. If we study the "negative shape" between the two front legs, on the reference we get a pretty clear trapezoid as shown here, whereas yours appear to be more arbitrary, not informed by the reference image.

Additionally, here are some notes about your second horse.

In a lot of ways the first horse was honestly a big move in the right direction. It showed vastly more attention being paid to observation and study of your reference, and while you definitely still need to work on your use of additional masses, these show a move in the right direction as well.

I'm going to ask that you redo the revisions I asked for. 5 more pages of animal constructions, with the same restrictions as before. Please read them more carefully this time, and be sure to adhere to them through each and every drawing.