Starting with your squirrel, this one's pretty well done. The tail on the back there has some issues - you didn't draw it in its entirety (it got cut off when it hit the body so it reads more as a flat shape rather than a solid 3D form) and you way overdid it with contour lines as well. The main body of the squirrel is pretty good though.

The wolf has a lot of major issues:

• Most of all, you're really not observing your reference carefully enough here, so your proportions are completely off. One thing that helps a lot with this is paying attention to the "negative shapes" created by the various parts of the animal's body. For example, if we look at the shapes that exist between the wolf's legs, we can see just how far off your own construction is. Keeping those negative shapes in mind as you construct the body will help you maintain a closer relationship with your reference material. The goal certainly isn't to create a perfect copy, but your wolf drawing definitely suggests you allowed yourself to spend too long drawing without looking back at your reference frequently enough.

• With head construction, it's very important that you stick with the core head construction I shared with you previously, because it provides a foundation upon which we can build upon. From what I can see, you probably read through it, but you weren't really attempting to apply it as directly to your drawings as you could have. Things like the specific eye socket shapes, minding the brow ridge, and so on ended up falling by the wayside. As you can see where I drew on top of the wolf reference itself, I would definitely consider the "cranial ball" we start out with to be MUCH smaller than the whole furry mass we can see in the reference. This is one of those things you'll develop an instinct for as you do more animal studies, but in general always try to work with smaller forms rather than committing yourself to a ball that occupes the whole visible space of the head. It's much harder to do that and then pull back, and so you end up with really exaggerated proportions.

• For the legs, I'm noticing that as you draw additional masses, you seem to be trying to keep the resulting silhouette of the leg very smooth and simple. When we add additional masses to a structure, we're inevitably going to end up with these little "pinches" formed by two or more outward curves meeting together. This occurs when we respect the fact that each new mass is its own volume, its own entity being incorporated into the structure. We can't simply smooth them out based on what we want to achieve - we have to take them into consideration and allow each additional mass to bring a bit of its own volume to the structure. As a result, those 'pinches' help create a more complex silhouette that still reads as solid and believable, and can help imply things like musculature.

For the rabbit, I did notice that you were building up some of your additional masses without really thinking about how you ought to design those silhouettes, as shown here. Consider where you use inward vs. outward curves more carefully.

All in all, I think you're moving in the right direction but still have a ways to go. Take what I've laid out here and try another 3 animal constructions. I'm adding one additional restriction as well - for these 3 constructions, you are not allowed to use the kind of contour lines that just sit on the surface of a single form. Those that define the intersection between forms are still allowed, but not contour lines like these.