TRANSACTIONS OF SECTION D. 405 
Amongst the fishes, the Dipnoi have enormous red cells, those of Ceratodus 
forsteri being 39 X 23 to 25 mw. The Elasmobranchs have also large cells, 
varying from 18X12°5 to 23x13°5y Amongst Teleostean fishes the size is much 
smaller. The cells are also rounder. In Vherapion unicolor they are nearly 
spherical in size 6 to 8 w. Other species range from 9X7 up to 13°5x10°3 yw 
in a catfish. 
The reptilia, snakes, lizards, and tortoises have red corpuscles ranging usually 
from 16 to 219 to 11 uw, though in some cases, as in the genus Hygosoma, the 
size tends to be smaller (14 to 168 to 10 x). 
Batrachians show red cells usually of from 18 to 20x10 to 144. 
Amongst birds, the emu has the largest (15°5 to 16°5x8°5 to 9°5 mw). The 
Pedicipediformes, Sphenisciformes, Ardeiformes, and Pelecaniformes come next 
(approximately 148 uw.) Charadriiformes are generally a little smaller. The 
pigeons, hawks, parrots, kingfishers, and cuckoos come next, the kingfishers 
being perhaps the largest of these. In the Passerine birds there is a definite 
tendency to smaller cells, ranging from 10 to 12x5 to 7 mw, with the exception 
of the family Corvide, where the size approximates more to the previous group. 
These figures seem to indicate that with specialisation has eventually come, 
both in fishes and in birds, a diminution in size of the red cells. The cumber- 
some corpuscles of Ceratodus have doubtless played a part in the gradual 
extinction of the Dipnoan fishes. The relationship of the various classes to each 
other is clearly shown in the size of the red cells. 
4. Notes on some Australian Hematozoa. 
By J. Burton Cizvanp, M.D. 
Owing to the geographical isolation of Australia, the study of the blood para- 
sites of the vertebrates, especially of such as have no easy means of passing 
over stretches of ocean, is of considerable interest. In some cases, such as the 
marsupials, interesting speculation arises as to whether the Hematozoa found 
in them reached Australia (1) with the marsupials when these originally came; 
or (2) as parasites of the invertebrate host by a separate arrival; or (3) whether 
their appearance represented the adaptation in Australia of a parasite, at one 
time confined to an invertebrate host, to a habitat partly in the vertebrate and 
partly in the invertebrate host. 
In marsupials Hzmogregarines have been found. Breuil has recorded in a 
bat the presence of a Trypanosome and of a Plasmodium. In birds, Plasmodium 
precox has been recorded in a falcon, and a Plasmodium has been found in the 
black swan. Plasmodium has also been recorded in the introduced sparrow. 
Plasmodium seems to be rare in birds compared with the presence of Halteridium. 
Halteridia are common in Australian birds, and have been found in all the 
States with the exception of Tasmania, though they have been found on 
Flinders Island in Bass Straits. The appedrances of the forms found vary 
somewhat, suggesting specific differences. Trypanosomes have been found in 
several species, but seem confined more especially to Queensland and northern 
New South Wales. With the same distribution, and often in the same infected 
birds, large parasites may be found in distended red cells. The parasite in the 
red cell is spherical and indents the nucleus of the host-cell, which is stretched 
over it so as to form a cap. I am of opinion that this is the intracorpuscular 
form of the Trypanosome with which it is usually associated, although my 
former colleague, Dr. Harvey Johnston, who was associated with me in first 
describing this form, has since referred to it as a Leucocytozoon, as does 
Breinl. The corpuscles are certainly not elongated in the remarkable way in 
which they are in infections by Leucocytozoon ziemannii. Microfilarie are 
common in birds. 
Reptiles.—Hemogregarines are common in snakes and lizards. Trypano- 
somes and Hemogregarines are met with in tortoises, as well as a Hmo- 
cystidium. A Hemocystidium has been met with in a gecko, and microfilaria 
in the water lizard, Physignathus lusueurii. 
