The MPSW55G is manufactured in a plastic TO-92 case. When looking at the flat side with the leads pointed downward, the three leads emerging from the transistor are, from left to right, the emitter, base, and collector leads. Here is an image showing the pin diagram of this transistor.
Complementary NPN transistor
The complementary NPN transistor to the MPSW55G is the MPSW05G.
SMD Version of MPSW55G transistor
The BCW89 (SOT-23), FMMTA55 (SOT-23), KST55 (SOT-23), MMBTA55 (SOT-23), PZTA55 (SOT-223) and SMBTA55 (SOT-23) is the SMD version of the MPSW55G transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.