Symbols in early 1600s baptismal records

I was looking at the baptismal records for the children of Martin Fernandes de Vaulus and Isabel de Grijalva y Velasco. They were baptized in Aguascalientes in the period 1618-1634. Their names were given as "Catalina +", "Isabel +", "Jacinta +", "espagnol +" (for Geronima), and "Pedro +". These are in the first film of Aguascalientes baptismal records.

My first thought was that these children had died soon after baptism, but in Jacinta's baptismal record, the baptism date is 25 de Abril 623, and it reads (in part) "Bautise con agua ... ... por la necessd urgente ..." and concludes with "Puse de los olios a 3 de diziembre de 623 fueron madrina Maria de Gabadi su abuela." (Film for Baptisms 1616-1660, image 22). She clearly did not die soon after baptism.

Some names will have the +, and some will not. It is there for both the Spanish and the Indians.

There are a few records marked with a Maltese cross; see record for Juana daughter of Francisco Macias Valades and Jacinta de Ortega (same film, image 32).

I am sure the "+" is the Cross, but what does the it mean, or why is it used only sometimes?

George Fulton