Rearrange the parts of the sentence, labelled X, Y, and Z, to form a coherent sentence. Such are the strata which we X: species as those now living in the Mediterranean Y: meet with in the south of Sicily, filled Z: with shells for the most part of the same

Introduction / Context:
This sentence arrangement question uses a more formal, almost scientific tone to describe geological strata. The sentence talks about layers of rock found in a particular region and what kind of shells they contain. Our job is to put the labelled parts X, Y, and Z in the correct order so that the sentence is grammatically correct and logically clear.

Given Data / Assumptions:
The given stem and labelled fragments are as follows.

Stem: Such are the strata which we
X: species as those now living in the Mediterranean
Y: meet with in the south of Sicily, filled
Z: with shells for the most part of the same
The completed sentence must describe where such strata are found and what fills them.

Concept / Approach:
First, notice that the phrase meet with in the south of Sicily, filled, contained in Y, is a natural continuation after the relative clause marker which we. The structure which we meet with in the south of Sicily is grammatically sound. Next, Z begins with with shells for the most part of the same, and this naturally follows filled from Y to form filled with shells for the most part of the same. Finally, X gives species as those now living in the Mediterranean, which logically describes the shells mentioned in Z. So the most coherent order of the fragments is Y, Z, then X.

Step-by-Step Solution:

Verification / Alternative check:
The reconstructed sentence reads Such are the strata which we meet with in the south of Sicily, filled with shells for the most part of the same species as those now living in the Mediterranean. This version is grammatically correct and expresses a clear scientific idea. If we try a different order, such as XYZ or XZY, we get awkward sequences like Such are the strata which we species as those now living in the Mediterranean meet with in the south of Sicily, filled, which are not acceptable. Therefore, YZX is the only ordering that produces a fluent and accurate sentence.

Why Other Options Are Wrong:
Option YXZ gives Such are the strata which we meet with in the south of Sicily, filled species as those now living in the Mediterranean with shells for the most part of the same, which is ungrammatical and breaks the natural phrase filled with shells. Option XZY starts incorrectly with species as those now living in the Mediterranean right after which we, which does not make sense. Option XYZ and ZXY also result in broken or incomplete grammatical structures and do not maintain the logical progression from location to contents to species description.

Common Pitfalls:
Learners can be misled by the presence of the word species in X and try to place it earlier in the sentence, thinking it must appear closer to strata. However, English relies on smaller units such as fixed phrases and relative clause patterns. A better strategy for these questions is to identify which fragments complete a grammatical structure like meet with in or filled with and then add descriptive phrases afterwards. This method helps avoid guesswork and leads to the coherent YZX order.

Final Answer:
The correct order is YZX, giving the sentence Such are the strata which we meet with in the south of Sicily, filled with shells for the most part of the same species as those now living in the Mediterranean.