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  JOURNAL
  OF
  THE PROCEEDINGS
  OF
  THE LINNEAN SOCIETY.

  ZOOLOGY.

  VOL. IV.

  LONDON:
  LONGMAN, GREEN, LONGMANS AND ROBERTS,
  AND
  WILLIAMS AND NORGATE.
  1860.

  PRINTED BY TAYLOR AND FRANCIS,
  RED LION COURT, FLEET STREET.


  LIST OF PAPERS.


                                                                  Page

  GARNER, ROBERT, Esq., F.L.S.
    On the Shell-bearing Mollusca, particularly with regard to
      Structure and Form                                            35

  HANLEY, SYLVANUS, Esq., F.L.S.
    On the Linnean Manuscript of the 'Museum Ulricae'                43

  HUXLEY, Prof. T. H., F.R.S., F.L.S., F.G.S., Professor
      of Natural History, Government School of Mines.
    On the Dermal Armour of _Jacare_ and _Caiman_,
      with Notes on the Specific and Generic Characters of recent
      _Crocodilia_                                                   1

  SALTER, S. J. A., Esq., M.B., F.L.S., F.G.S.
    On the Moulting of the Common Lobster (_Homarus vulgaris_)
      and Shore Crab (_Carcinus maenas_)                             30

  SANDWITH, Hon. H., M.D., C.B., Colonial Secretary of
      the Mauritius.
    On the Habits of the "Aye-Aye" (_Cheiromys madagascariensis_,
      L., Cuv.)                                                     28

  WALKER, FRANCIS, Esq., F.L.S.
    Catalogue of the Dipterous Insects collected at Makessar, in
      Celebes, by Mr. A. R. Wallace, with Descriptions of New
      Species                                                       90

  WALLACE, A. R., Esq.
    On the Zoological Geography of the Malay Archipelago           172

  INDEX                                                            185




JOURNAL OF THE PROCEEDINGS

OF THE

LINNEAN SOCIETY OF LONDON.




On the dermal armour of _Jacare_ and _Caiman_, with notes on the
Specific and Generic Characters of recent _Crocodilia_. By T. H. HUXLEY,
Esq., F.R.S., F.L.S., Prof. of Nat. History, Gov. School of Mines.

[Read Feb. 17th, 1859.]


In the course of a recent investigation into the nature of the singular
extinct reptile, _Stagonolepis_, I was led to inquire somewhat
minutely into the character of the exoskeleton, or dermal armour, of
the existing _Crocodilia_. To my surprise, I found that very little
detailed information on the subject was to be obtained from the standard
repertories of Comparative Anatomy, or even from the special monographs
on Crocodilian structure and classification; but I was still more
astonished to discover, among whole genera of recent _Crocodilia_,
an exoskeleton possessed of characters such as have been universally
supposed to be peculiar to long extinct forms of the order, and whose
existence in any recent species has hitherto, so far as I can ascertain,
been completely overlooked.

The attempt to discover the limits within which this remarkable
exoskeleton is to be found, led me to look, more critically than I had
previously done, into the arrangement and specific characterization
of the recent _Crocodilia_. I have thereby arrived at results which,
imperfect as they are, may be of service by leading others to inquire
into the exact characters of species not at present within my reach;
and I therefore propose to preface my account of the peculiarities of
the exoskeleton in two of the genera of recent Crocodiles with some
remarks on the classification of the group, and with a few notes upon
the characters of the species and the limits of the genera.

Everyone is acquainted with the great improvement effected in this
branch of Herpetology by Cuvier, who divided the Crocodiles, which he
regarded as constituting only a single genus, into the three subgenera
_Alligatores_, _Crocodili_, and _Longirostres_. Subsequent writers
have admitted these highly natural subdivisions; but there has been a
constant tendency to raise their rank. The genus _Crocodilus_ has become
the order _Crocodilia_; the subgenera _Alligatores_, &c., have been
elevated into families; Dr. Gray has shown that the _Alligatores_ must
be divided into three genera, and that there are at least two genera of
_Crocodili_; and, while one of Cuvier's species of _Longirostres_ has
been suppressed, the group is very generally retained with a changed
name (_Gavialis_), a very important addition having been made to it in
the _Crocodilus Schlegelii_ of Mueller and Schlegel.

Unless the considerable materials contained in the British Museum, the
Hunterian collection, the collection of Dr. Grant, and the Christchurch
Museum at Oxford had been freely placed at my disposal, I should have
been wholly