Complex sentence: Normally there are 8 upper labials, the fourth and fifth entering the eye and 5 lower labials in contact with the anterior chin-shields, which are as long as the posterior or a little longer.
Split into simpler sentences: Normally there are 8 upper labials, the fourth and fifth entering the eye, and 5 lower labials in contact with the anterior chin shields. The anterior chin shields are as long as the posterior chin shields or a little longer.