Magellanic spiral

A Magellanic spiral galaxy is a spiral galaxy with only one spiral arm. Magellanic spiral galaxies are classified as the type Sm (with sub-categories SAm, SBm, SABm); the prototype galaxy and namesake for Magellanic spirals is the Large Magellanic Cloud, an SBm galaxy. They are usually smaller dwarf galaxies and can be considered to be intermediate between dwarf spiral galaxies and irregular galaxies.

Magellanic spirals
SAm galaxies are a type of unbarred spiral galaxy, while SBm are a type of barred spiral galaxy. SABm are a type of intermediate spiral galaxy.

Type Sm and Im galaxies have also been categorized as irregular galaxies with some structure (type Irr-1). Sm galaxies are typically disrupted and asymmetric. dSm galaxies are dwarf spiral galaxies or dwarf irregular galaxies, depending on categorization scheme.

The Magellanic spiral classification was introduced by Gerard de Vaucouleurs, along with Magellanic irregular (Im), when he revamped the Hubble classification of galaxies.

Barred (SBm)

 * Large Magellanic Cloud (LMC; prototype galaxy)
 * Small Magellanic Cloud (SMC)
 * NGC 1311
 * NGC 4618
 * NGC 4236
 * NGC 55
 * NGC 4214
 * NGC 3109
 * IC 4710

Intermediate (SABm)

 * NGC 4625
 * NGC 5713

Unbarred (SAm)

 * NGC 5204
 * NGC 2552