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OF THE

BRITISH NON-PARASITICAL WORMS

IN THE

COLLECTION

OF THE

BRITISH MUSEUM.

BY

GEORGE JOHNSTON, M.D. EDIN.,

FELLOW OF THE ROYAL COLLEGE OF SURGEONS OF EDINBURGH;
AND LL.D. MARISCHAL COLLEGE, ABERDEEN, ETC.

LONDON:

PRINTED BY ORDER OF THE TRUSTEES.

1865.

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PREFACE.

THE publication of this Catalogue of British Non-parasitical Worms has been delayed, owing to the lamented death of the author, DR. JOHNSTON, while it was still in the Press. A Supplement, prepared by Dr. Baird, containing addenda, corrigenda, and a notice of additional species found since Dr. Johnston's death, with a complete index, have been added, to render the work more complete.

8th February, 1865,

J. E. GRAY,

A CATALOGUE

OF THE

BRITISH NON-PARASITICAL WORMS.

THE Helmintha or Worms are invertebrate soft animals, symmetrically bilateral, or with the viscera arranged on the sides of a longitudinal axis. They are never organically attached to foreign bodies or their own cases, and are capable of progression to a more or less extent. They move forwards, some by a continuous gliding, some by a succession of trails, some by undulations in the water, and others by means of soft appendages and bristles placed along the sides. Diesing's definition of the class is as follows:- "Animalia evertebrata, inarticulata (i. e. extremitatibus articulatis nullis prædita), nunc mollia aut elastica, ebranchiata, setis retractilibus nullis (Achæthelmintha); nunc mollia, ebranchiata v. branchiis externis munita, setis retractilibus instructa (Chathelmintha)."

There are two kinds of Worms,-one which are found within the viscera of living animals, and which cannot maintain their existence in any other situation; and another which lead an exterior life, either entirely independent, or as the external parasites of some aquatic animals. These, however, the parasites can forsake at will, without incurring the penalty of death. It is the second kind of Worms to which this Catalogue is restricted; and they may be conveniently included in the following Orders :

A. APODOUS: the body without bristles on the sides. = Apoda, Macleay. Achæethelmintha, Diesing.

=

* Body exannular.

I. Order. TURBELLARIA. The extremities of the body simple and continuous with it: no distinct head.

B

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