Trying to understand Mexican death records

I hope someone can help me understand how to find death records.
For instance, I tried to find a record for Marciala Guerrero in the
Defunciones Civil Records for Jalisco, Tlajalmulco, 1917-1924. In the
index where I found her name (image 385) there was #159 before her name
and #51 after. What do the numbers refer to? I never did find this record.
Is there some kind of order as to how to find the index? In searching one
by one, I found several records for children within the same pages, so I
wondered if this was done for a reason.
Thanks.
Nancy