(concurring specially) :
I concur upon the basis of the law as stated in Hanks v. Hales, 17 Utah 2d 344, 411 P.2d 836, to which I refer in order to avoid repetition here. See also Greener v. Greener, 116 Utah 571, 212 P.2d 194. I am not sure that in practical application to any given fact situation there would be any substantial difference between the statement I refer to and the principle as stated in the main opinion. But in view of the fact that these joint tenancy account contracts are often used for some special purpose, in my judgment it is important to tie in certain previously expressed ideas: (1) that as to an account in joint tenancy there is a presumption that the agreement is as expressed therein; (2) that as to the depository, under its agreement, it would be protected upon payment to either joint tenant or his proper representative; (3) that as between the parties or their representatives the agreement is presumptively valid and must be given effect unless under equitable principles it is shown by clear and *210convmcing evidence that there was a different arrangement or agreement between the parties. Analogous are situations where a deed, though absolute in its terms, under appropriate circumstances can be held to be in effect a mortgage as between the parties. See Corey v. Roberts, 82 Utah 445, 25 P.2d 940; Gibbons v. Gibbons, 103 Utah 266, 135 P.2d 105, and Thornley Land & Livestock Co. v. Gailey et al., 105 Utah 519, 143 P.2d 283.