You do not see the single scalar because all arguments passed into a subrutine are flatened into a list. So when you call your sub cog_class(@somearray, $somescalar); the $somescalar variable and @somearray all became @_ in the subrutine.

If you only need one array and one scalar just switch them places cog_class($somescalar,@somearray); and if you need more complex data structures unchanged I suggest passing it by reference.

And another thing, you can't use those scalars by name in the sub unless you take them out of @_, you can do it like this:

#!/usr/bin/perl
use warnings;
use strict;

my $scalar = 'a';
my @array  = qw(1 2 3);
some_sub($scalar,@array);

sub some_sub {
 my $scalar = shift; # take the first element out of @_
 # and the first element in this case is $scalar with 'a'  
 # inside
 my @array = @_; # pass all the remaining arguments into 
 # @array so it now contains 1,2,3
}
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I suggest that you read more about subrutines in the:
perldoc perlsub