Hi! I'll be critiquing your work today.

Organic intersections - These look good for the most part, though there are some key flaws, since in some areas it looks like: you forgot to establish any contour lines on the form (making them seem somewhat flat) or drew them in a confusing way (see the bottom-left form on the first page); you didn't finish drawing the outline of the form (see the top-right form on the first page); or your shadows didn't properly follow the contour of the form it was falling on (see page 2) or contradicted each other in general, making it confusing as to what it is in front of each other. Overall quite good, but these small mistakes do detract from it.

Birds - These both look quite good, and the forms feel very solid and 3D, though the wing on the first bird might be a bit small (I'm not sure though since I don't have the original reference image). Overall, great job!

Foxes - First fox: looks great. It was a very smart idea to establish the perspective with the plane at the bottom before drawing. When adding additional forms, I'd suggest drawing them as one, continuous form, instead of the individual blobs you drew on the fox's back. Second fox: The form feels quite solid, but the bottom region is quite confusing with all of the overlapping lines. I'd suggest adding line weight and shadow to certain areas to make them more distinct and readable.

Oryx - Looks good, very solid form. The rocks in the background of the second one feel kind of like they're floating, so I'd suggest adding another straight line (higher up then the one you've already established) so that it's clear that they're on the ground.

Bears - In terms of form these are okay - though the bear does appear a bit too sausage-like in shape and a bit unstable. In terms of proportions I feel that these are lacking a bit (however proportions and accuracy aren't really the focus of this exercise, so this doesn't matter). In general I would suggest adding some more contour lines to your forms, as this can help to give them greater solidity.

Rhinoceroses - The thigh sizes on the first rhino seem a bit too small, however I can't say this for certain since (again) I don't have the original reference images for these. Overall, okay.

Barreleye Fish and Whale Shark - The smooth gestural lines (which didn't have as much time to shine in your previous drawings due to their other issues) give these drawings a great effect. Both drawings feel very solid and confident, and it's clear what's happening in the image. These look great!

Hybrid (if i'm not mistaken, this is the last image) - feels very solid, good implementation of different animal features.

Overall, quite good understanding of form and structure (though with a couple of issues did crop up). I'd suggest redoing the Organic Intersections exercise, implementing my critiques as you do so.