# [Jelly], 138 bytes

    ḲḊm2iⱮ“Q®ḃƁ⁼ṇÑ1¿Ọɠ\ƥȥ⁼ṙ⁴EŀƥŒEæʋØ>þ>⁴þʋ[⁾Ƒ]eÞḍ8ß®ⱮȮø⁹ç÷R?g®=,¥ėµ@ØU~"/Xçq®ÆƬ°ɠsṭṭ?dC#Ċ?gѶPÇH5p@ʂEœ⁹½G6ḌƘṪµɦ8€(S¦Ḥ⁸ṫ"ḟḢlṾ¦ƤḃƭẊ@’ḃ4$ÄṬk⁹¤ịØa

[Try it online!][TIO-k4lxj0js]

[Jelly]: https://github.com/DennisMitchell/jelly
[TIO-k4lxj0js]: https://tio.run/##pVRLbxMxEP4ro8KBA2MEAtQLTSQUwZGHkJCAQ6EhtE2hpbzKAWVLRaW0HAIHUgnRCiWpBOkKEIVdCkGym1WTf@H9I4ud7trjtDeSrNeexzfzzYwzVSyXF5JEBt9kUJ05NRl/9ePK@8vcl8HLyIu93zJcFrWT/K/cWe1t3Iyae82BcC32vhe6lajZfVMQrf6KqI@JzpgSik5/5UbsdaLaraL4IIPXo2Kd@wp2zxdB7IViU/y8kitx/9xx3tx9x7fzon7txciJ62JzjvviVdTmX3ob8zLcUr/cxPkju9VcSdT4j0ti@eKZ2Xx/sdB9q3D4nwtnZbAa1WX4iW/3WqPxYvvYVd6SQSP2Ahl@HpHBugw@lmXY4a2ooflsyV/VfFxZU/vTR8WSDNvTGqkhd1T@40mSjANDuA3IGIM76oUMJvQJisDgLjAtKAGq9Z46KPmkesGU8kKEae0AZXVQshllBfeVBB6AVs5qGwZz2hnhoTaCeY0BjwDhsYaGJ/qM8FSbwjMdF2FBgyI8134s0XvUO40yOAwenVf2SZX7osEOqZQh2pOrYakXZt9BKDRw@9YmnImSmg2FTpfUPMVHY57SYM5ifDM9iYAursk4UxgAy5IwtiUy1mjQhhDTBKwSM9oZAq08KR@pmknVppk2LePtFIA5GaBJn2U0SIpWZUtFqblUTB5OkyzJA/VnTqdsRQhfEwkNJTpxw4V32mdGDw828rCIaHeYeZJ6m2SRURGdWyQ46NyCA2na@tnuWN6M5EOmCm1uSMpm6mG7x4hbNt@u1NJBSnHofjp3yg4gLSRtop0YJBzJbP7fdXFnmdk5Z4f@P2WTqDX/AA "Jelly – Try It Online"

A dyadic link taking the library as the left argument and the Morse code input as the right argument. Returns a Jelly string of the lyrics. The long integer that takes the majority of the code has the lengths of each Morse code character encoded within it. 

## Explanation 


    Ḳ                         | Split at spaces
     Ḋ                        | Remove first item
      m2                      | Take odd items (i.e. Morse code representations of letters a..z)
        iⱮ              ¤     | Find index of these in each of the following:
          “Q...@’             | - Base-250-encoded integer 742925387377430937422864458121941352705403867269973650879937105837755604647313120541399315429452997316260711263757137193164236124383957174543961671910365268304120327243209050996915401898167278257845227193061059012165352924148307417330452740236835399667569278751322913192633409885614815
                 ḃ4$          | - Bijevtive base 4
                    Ä         | - Cumulative sum
                     Ṭ        | - Convert to logical list with 1s at the appropriate indices
                      k⁹      | - Split right argument at those positions
                         ịØa  | Finally, index into lowercase letters