Vlll
PREFACE.
unnecessary to burden the text; and, under the head of Bibliography, I have given some references to the literature of the subject which may be useful to those who wish to follow it out more fully. I am indebted to Mr. T. J. Parker, demonstrator of my biological class, for several anatomical draw¬ ings ;
and for valuable aid in
supervising the
execution of the woodcuts, and in seeing the work through the press. Mr. Cooper has had charge of the illustrations, and I am indebted to him and to Mr. Coombs, the accurate and skilful draughtsman to whom the more difficult subjects were
entrusted, for
such excellent specimens of xylographic art as the figures of the Crab, Lobster, Eock Lobster, and Norway Lobster. T. H. H.
London,
November, 1879.
