Joseph.Ginder@CMU-CS-SPICE.ARPA (01/26/84)
The book described in sfl v9.18 about the young boys scuba diving and the lizard creature is called "Stranger from the Depths" (or something close to that). It is by Gerry (Gary?) Turner; I remember reading it in a Scholastic Book Club edition many years ago. Excellent juvenile SF; but as I remember, OK for adults also. I'm sure I still have this book somewhere. The vehicle which penetrates rock by melting it was called a "mole". I remember that the lizard creatures in the underground cities all had names with double vowels or some other characteristic spelling depending on which city they were from.