Hi Tidesphere,

That's a good question. When I was drawing the additional masses on the back of the horse I was applying the logic shown in this diagram and using it to rebuild an approximation of the long mass you had along the top of the back there. The reason I broke it into pieces (the two red ones first, then the purple one) was to avoid pushing an inward curve into the top of the mass, where it is exposed to fresh air and there is nothing to press against it. (It's the same issue I noted on the underside of the belly here albeit a subtler example.)

With the additional information present in your reference image I would design the masses a little differently- although still thinking of them as pieces of clay to wrap around the other structures in the construction.

First though, I'm noticing some observational/ spatial awareness issues that I'd like you to be aware of. If we look along the top-line of the animal, we can see that the top of the bump above the shoulders is lower than the top of the rump, but in your construction this relationship is reversed. I know it is difficult to become sensitive to these kinds of relationships, though there are "clues" in your reference we can pick up on. Firstly, there are a lot of horizontal lines on the wall behind the horse, which make it apparent that the top of the animal is not horizontal. Second, we can look at the positioning of the feet which (as far as I can tell, given that part of your drawing seems to be cropped off in your photo) you observed fairly accurately. If the front feet are lower than the hind ones, then it stands to reason that the shoulders may also be lower than the rump.

Furthermore, although I see from your contour curves that you identified that the front end of the horse is closer than the rear end, you'd still constructed your major masses as though we're looking at the horse side-on, rather than the three-quarter view we see in the reference. In all fairness, most of the demos for this lesson feature animals being viewed side-on so this isn't something I'd expect you to know, but it is something I'd like you to think about. As the animal turns in space the major masses and the spaces between them will foreshorten. You'd done a good job with the head and neck, but I'd like you to take a look at this image where I've done a block in of the major masses (directly onto the reference to save some time) and notice that as the animal starts to turn more towards the viewer, the gap between the rib cage and pelvis appears to get smaller, and eventually the pelvis mass will pass behind the rib cage, as you can see in the drama puma on the informal demos page. I can see from this cat that this is something that you can pick up on, some of the time, and maybe find it harder to identify when the angle is more subtle. In this case, there is a thought exercise you can use to help identify what angle we're looking at the animal from, and that is to think about the body as a box. If we were to simplify the body into a box, what direction would that box be facing? Here is a rough example of what I mean (please excuse the shoddiness of the boxes here) although I would never actually draw these boxes as part of the animal construction, thinking this way- about how much of the front, side, top or bottom of the box we can see, can help a lot in figuring out how the animal is oriented in space, and we can use that information to place the major masses accordingly.

Anyway, circling back to your actual question about the additional masses, based on the new information in your reference, I'd agree that we don't actually need a mass in the middle of the back, we can use the sag of the torso sausage as it is for the dip we seen in the middle of the back. I'd still use an additional mass for the protrusion above the shoulders, and focus my attention on the smaller masses along the rump and legs as shown here.

The difficulty I'm finding is making the sausage shape in a way that isn't just... the entire torso on its own, with no need for extra forms. But I know I'm not supposed to do that, so I make the sausage form smaller than the torso, and then... what forms do I put on it that isn't just "wrap material around the torso to make it the same shape but just bigger"?

The idea we're going for with these constructions is to start as simply as possible, and gradually build up complexity piece by piece. We're not drawing a sausage form, then building the same form but bigger. Use your core construction to capture as much of the mass of the animal as you can, while still keeping to the simple characteristics discussed earlier. Sometimes the torso sausage is a pretty good fit for the animal, and sometimes we need to add extra mass over the shoulders, hips, or for a hump in the middle. Even when we do get most of the animal captured with the torso sausage, I'd like you to do your best to carefully observe your reference for subtler elements, smaller bumps and ridges, and be as sensitive as you can to the nuances that make that particular animal look the way it does.

....

I had already written the above before I saw your edit.

Responding to your edit:

It is mildly frustrating that you pushed ahead without waiting for a response to your questions, but I do understand your eagerness to get on with your constructions, and this is a big improvement.

You've kept your major masses and torso sausage simpler (good work) though the rib cage mass should occupy roughly half the length of the torso.

You're sticking more closely to the sausage method for constructing your legs, but don't neglect the ellipses for the shoulder and thigh masses. You'll find Uncomfortable discussing them in this section of the wolf demo, and they're shown with the blue ellipses on this horse.

There are a couple of other points to note but we don't have the resources for TAs to critique work piecemeal, and so you do need to submit everything together, as assigned. While that puts more work on you (in terms of giving you more room to end up making the same mistakes more than might feel necessary), it is necessary to put that on the student (as explained here in Lesson 0) due to the extremely low price at which our feedback is offered. If you'd like additional feedback before all 5 pages are completed you can post on the Discord server, and another student may chip in with advice, or I may take a look if I have some free time.