We discuss the nature of the galaxies found in the Pico dos Dias Survey ( PDS ) for young stellar objects .
The PDS galaxies were selected from the IRAS Point Source catalog .
They have flux density of moderate or high quality at 12 , 25 and 60 \mu m and spectral indices in the ranges -3.00 \leq \alpha ( 25 , 12 ) \leq + 0.35 and -2.50 \leq \alpha ( 60 , 25 ) \leq + 0.85 .
These criteria allowed the detection of 382 galaxies , which are a mixture of starburst and Seyfert galaxies .
Most of the PDS Seyferts are included in the catalog of warm IRAS sources by de Grijp et al .
( 1987 ) .
The remaining galaxies constitute a homogeneous sample of luminous ( \log ( { L } _ { B } / { L } _ { \odot } ) = 9.9 \pm 0.4 ) starburst galaxies , 67 % of which were not recognized as such before .

The starburst nature of the PDS galaxies is established by comparing their L _ { IR } /L _ { B } ratios and IRAS colors with a sample of emission line galaxies from the literature already classified as starburst galaxies .
The starburst galaxies show an excess of FIR luminosity and their IRAS colors are significantly different from those of Seyfert galaxies – 99 % of the starburst galaxies in our sample have a spectral index \alpha ( 60 , 25 ) < -1.9 .
As opposed to Seyfert galaxies , very few PDS starbursts are detected in X-rays .

In the infrared , the starburst galaxies form a continuous sequence with normal galaxies .
But they generally can be distinguished from normal galaxies by their spectral index \alpha ( 60 , 25 ) > -2.5 .
This color cut–off also marks a change in the dominant morphologies of the galaxies : the normal IRAS galaxies are preferentially late–type spirals ( Sb and later ) , while the starbursts are more numerous among early–type spirals ( earlier than Sbc ) .
This preference of starbursts for early–type spirals is not new , but a trait of the massive Starburst Nucleus Galaxies ( Coziol et al .
1997a ) .
Like in other SBNG samples , the PDS starbursts show no preference for barred galaxies .

No difference is found between the starbursts detected in the FIR and those detected on the basis of UV excess .
The PDS starburst galaxies represent the FIR luminous branch of the UV-bright starburst nucleus galaxies , with mean FIR luminosity \log ( { L } _ { IR } / { L } _ { \odot } ) = 10.3 \pm 0.5 and redshifts smaller than 0.1 .
They form a complete sample limited in flux in the FIR at 2 \times 10 ^ { -10 } erg cm ^ { -2 } s ^ { -1 } .