The posterior patagium, the fold between trunk and inner surface of the upper arm, is stretched by the metapatagialis muscle, which is composed of slips from the serratus, superficialis, latissimus dorsi and the expansor secundariorum muscles.

Carcharodon) and of toothed whales such as Squalodon serratus.

The larger shrimp-like crustacea are generally known as "prawns," the name being especially applied in Britain to the species Leander serratus, formerly called Palaemon serratus, which is highly esteemed for the table.

On the British coasts zones are observable in passing from high to low water mark, characterized by the prevalence of different species, thus: - Pelvetia canaliculata, Fucus platycarpus, Fucus vesiculosus, Ascophyllum nodosum, Fucus serratus, Laminaria digitata.

fucus serratus can tolerate losing about 40% and Laminaria digitata about 20% .