Add Jubjub bird image to the title page and cite Carroll references.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

protocol/protocol.tex

@@ -1652,9 +1652,17 @@ electronic commerce and payment, financial privacy, proof of work, zero knowledg
 \Large \coauthora\affiliation — \coauthorb\affiliation — \coauthorc\affiliation}
 \date{\today}
 \maketitle
+\vspace{-6ex}
+
+\notsprout{
+\begin{center}
+\hspace{0.6em}\includegraphics[scale=.1,interpolate]{jubjub}
+\footnote{Jubjub bird image credit: Peter Newell 1902; Daira Hopwood 2018.}
+\end{center}
+\vspace{-6ex}
+} %notsprout
 
 \renewcommand{\abstractname}{}
-\vspace{-8ex}
 \begin{abstract}
 \normalsize \noindent \textbf{Abstract.}
 \Zcash is an implementation of the \term{Decentralized Anonymous Payment}
@@ -6756,7 +6764,9 @@ curve.
 \sapling{
 \subsubsubsection{\Jubjub} \label{jubjub}
 
-The \representedGroup $\JubjubCurve$ is defined in this section.
+\Sapling uses an elliptic curve designed to be efficiently implementable in
+\zkSNARKCircuits, called ``Jubjub'' \cite{Carroll1876}.
+The \representedGroup $\JubjubCurve$ of points on this curve is defined in this section.
 
 Let $\ParamJ{q} := \ParamS{r}$, as defined in \crossref{blspairing}.
 
@@ -9137,6 +9147,11 @@ Daira Hopwood, Sean Bowe, and Jack Grigg. A potential attack linking
 found by Brian Warner.}
 
 
+\notsprout{
+Finally, we would like to thank the Internet Archive for their scan of
+Peter Newell's illustration of the Jubjub bird, from \cite{Carroll1902}.
+}
+
 \intropart
 \section{Change History}
 
@@ -9154,6 +9169,9 @@ found by Brian Warner.}
     \item Improve cross-referencing.
     \item Change the notation for a multiplication constraint in \crossref{circuitdesign} to avoid
           potential confusion with cartesian product.
+    \item Add the Jubjub bird image to the title page. This image has been edited from a scan of
+          Peter Newell's original illustration (as it appeared in \cite{Carroll1902}) to remove the
+          background and Bandersnatch, and to restore the bird's clipped right wing.
     \item Change the light yellow background to white (indicating that this \NUZero and \Sapling
           specification is no longer a draft).
 } %sapling

protocol/zcash.bib

@@ -1019,3 +1019,23 @@ Proceedings of the 14th Annual International Cryptology Conference
    url={https://www.researchgate.net/profile/Jeroen_Van_de_Graaf/publication/242379939_Multiparty_computations_ensuring_secrecy_of_each_party%27s_input_and_correctness_of_the_output},
    urldate={2018-03-01}
 }
+
+@misc{Carroll1876,
+   presort={Carroll1876},
+   author={Lewis Carroll},
+   title={The {H}unting of the {S}nark},
+   date={1876-03-29},
+   howpublished={With illustrations by Henry Holiday. MacMillan and Co. London.},
+   url={https://www.gutenberg.org/files/29888/29888-h/29888-h.htm},
+   urldate={2018-05-23}
+}
+
+@misc{Carroll1902,
+   presort={Carroll1902},
+   author={Lewis Carroll},
+   title={Through the {L}ooking-{G}lass, and {W}hat {A}lice {F}ound {T}here (1902 edition)},
+   date={1902-10},
+   howpublished={Illustrated by Peter Newell and Robert Murray Wright. Harper and Brothers Publishers. New York},
+   url={https://archive.org/details/throughlookinggl00carr4},
+   urldate={2018-06-20}
+}