94 Macieay Mermortat Vouvume. 
I.—Iyrropuctory. 
The receipt last year from Dr. von Jhering, of Brazil, through Mr. Chas. 
Chilton, of Port Chalmers, New Zealand, of a new form of the remarkable genus 
Temnocephala re-directed my attention to that subject, and I have made the study of 
the new form the occasion for a revision of the morphology of the whole group. 
The examination of new forms and of better specimens of the species previously 
described has led to the observation of a number of new points, some of which seem 
to me of considerable interest and importance. In the present communication I give 
an account of all that is known of the family, incorporating the results of more 
recent observations with such as have already been published,—illustrating by figures, 
however, only such features as have not been already represented, or have not been 
represented in a sufficient manner. 
I take the opportunity of expressing my thanks to Dr. A. Dendy, Professor 
Baldwin Spencer, Mr. Chas. Chilton, Professor T. Jeffery Parker, Sir James Hector, 
and Mr. Alex. Morton for supplies of specimens of various species. To Professor 
Spencer I am particularly indebted for specimens of the Gippsland burrowing 
crayfish (Exgeus fossor), with the Temnocephala that lives on its surface. 
Since I published a paper on Zemnocephala* there has appeared an important 
contribution to the subject from Professor Max Weber of Amsterdam,t and to this I 
shall have frequent occasion to refer in the following pages. In 1888 was published 
a valuable summary of our knowledge of the Trematodes under the title “Saggio di 
una Morfologia dei Trematodi,” by Dr. Fr. Sav. Monticelli of Naples; and the same 
author has also published two short papers—one entitled “Di una nuova specie del 
genere Temnocephala, Blanch., ectoparassita dei Cheloniani” and the other ‘“ Breve 
nota sulle uova e sugli embrioni della Temmnocephala chilensts” (‘ Att. Soc. Ital. di 
scienze naturali,’ Vol. XX XII.). The most important general work on the ecto- 
parasitic Trematodes that has appeared of late years is the part of the “ Wiirmer” of 
Bronn’s “ Klassen und Ordnungen des Thier-reichs,” by M. Braun, dealing with that 
group. This has been of very great assistance to me, especially in the absence of 
some of the original papers, such as Taschenberg’s. G. Brandes has recorded various 
observations on the minute structure of Zemnocephala brevicornis from Brazilf; and 
* «Quart. Journ, Micro, Sci.’ Vol. XXVIII. (1888), pp. 279-302, pls. xx.-xx1. 
+ ** Ueber Temnocephala, Blanchard,” ‘ Zoologische Ergebnisse einer Reise.’ etc. 
+ “Zum feineren Bau der Trématoden,” ‘ Zeitschr. f. wiss. Zool.’ LIII. p. 558 (1892). 
