146 Macuieay Memoria Vouume. 
On the whole, a review of the evidence seems to me to point to the conclusion 
that the Trematode affinities of Zemnocephala somewhat predominate over the 
Turbellarian. It presents an assemblage of characters which distinguish it very 
broadly from any individual member of the former class; but perhaps it has rather 
more important points of resemblance in the various features of its structure with 
now one now another ectoparasitic Trematode than with the Rhabdocceles. The 
large ventral sucker, the excretory sacs, and the nervous system may be set down as 
decidedly Trematode and not Rhabdoccele in character. The preponderance, however, 
if it occurs, is only slight, and I should see little reason for finding fault with anyone 
who should regard the Zemnocephalee as aberrant Rhabdoceeles specially modified in 
accordance with a peculiar mode of life. 
XVIL— List or tHe PrincipaL Works AND PAPERS REFERRED TO. 
Benepen, P. J. vay, and Hessz, C. E. Recherches sur les Bdelloides et les 
Trematodes marins. Mem. Acad. Roy. des Sci. Brux. (1864). 
Benepen, BE. van. Encore un mot sur le nephridium et la cavité du corps des 
Trematodes et des Cestodes. Zool. Anz. V. (1882). 
Beneven, P. J. van. Note sur lappareil circulatoire des Trematodes. Ann des Sei. 
Nat., 3@° Série, T. XVII. (1852). 
Brancuarp, E. Anularés in Gay’s Historia fisica y politica de Chilé (1849). 
Buomrretp. Review of recent researches in Spermatogenesis. Quart. Journ. Micro. 
Sci, XXIII. (1883). 
Bouma, L. Untersuchungen iiber Rhabdocdle Turbellarien. Zeitschrift f. wiss. 
Zool. LI. (1891). 
Branpes, R. Zum feineren Bauder Trematoden. Zeitschr. f. wiss. Zool. LI. (1892). 
Braun, M. Ueber die Lage des Excretionsporus bei den ectoparasitischen 
Trematoden. Zool. Anz. XI. (1889). 
Braun, M. Ueber Temnocephala, zusammenfassender Bericht. Centralbl.  f. 
Bacteriologie und Parasitenkunde, VIT. (1890). 
Burscuut, O. Bemerkungen iiber den excretorischen Gefissapparat der Trematoden. 
Zool. Anz. II. (1879). 
