The author considers stochastic differential equations of the form

$dx=\sigma x\phantom{\rule{0.166667em}{0ex}}db(t,a),$ $t\ge 0,$ $x\left(0\right)={x}_{0},$ $\sigma \in R$, where

$b(t,a):=1/\left({\Gamma}(a+1/2)\right){\int}_{0}^{t}{(t-\tau )}^{a-1/2}w\left(\tau \right)\phantom{\rule{0.166667em}{0ex}}d\tau $, and

$a$ is between 0 and 1. Here

$w$ is a normalized Gaussian white noise and

$b(t,a)$ is a normalized fractional Brownian motion of order

$a$. First some basic results on fractional derivatives, integrals and a Taylor expansion of fractional order are given. Then the solutions of some deterministic fractional differential equations are discussed and, finally, an application to geometric fractional Brownian motion is given. The solutions obtained involve the Mittag-Leffler function. Somewhat irritating is a misprint, namely

$\u25c3$ (or

$\u25b9$), which from the context may mean

$<$ or

$\le $ (or

$>$,

$\ge $) in different places, sometimes

$\le $ appears, too.