The electromagnet will be demagnetized and magnetized correspondingly with the condensations and rarefaction's of the mass of air,...and the armature.... will be set into vibrations similar to those of the membrane in the transmitting apparatus. (Legat's report, 1862 Zeitschrift)
The transmitter, Fig A, consists of a conical tube..... closed by a membrane... by speaking....into the tube....there will be evoked a motion of the membrane....(Legat's report, 1862 Zeitschrift)
That which has here been spoken of will still require considerable improvement, and in particular mechanical science must complete the apparatus to be used.-(Legat's report, 1862 Zeitschrift)
Bell did give Reis credit by name in the paper entitled "Researches in Electric Telephony" which he presented at the Academy of Arts and Sciences in May of 1876 and then at the Society of Telegraphic Engineers, November, 1877. Bell also references Reis's work in an article written by Professor Bottger in Dingler's "Polytechnic Journal" 1863.
The following link will show excerpts from Bell's and Reis's notebooks.