The state of Yugoslavia provides both an abundant and important source for zoological studies owing to its varied geographical, climatic and ethnographic conditions. To the student of ticks especially there is hardly a country in Europe which offers as large a field for study as Yugoslavia. Therefore I trust a short description of the Yugoslavian ticks and their biological habits, so far as known, will be of some interest.

The oocysts studied were concentrated from the contents of the colon and caecum of the cottontail rabbit. The concentration method of Benbrook (1929) has been found to serve best.

1. Two new species of Xiphidiocercariae have been described. These two forms have been designated as C. lühei and C. gopyjungi.

2. The flame-cell formula of C. lüheiis 2 × 3 × 3 = 18 and that of C. gopyjungi is 2 × 4 × 3 = 24.

3. It is shown that C. gopyjungi has the characters of both the subgroups Polyadena (Cort) and Daswan (Sewell), and the group Cercariae armatae is redefined.

4. Further, two new species of furcocercous cercariae have been described. They have been designated as C. ajmeri and C. anasagari.

5. It has been pointed out that the types of excretory systems as met with in C. ajmeri and C. anasagari are of extreme importance from the evolutionary point of view and fill in gaps in Sewell's (1930) evolutionary scheme.

6. The latter two species have been listed in their proper position in Miller's (1926) scheme of classification of the furcocercous cercariae.

Many great men have said that no science is really worthy of the name until it has attained quantitative accuracy and can express its principles and laws in mathematical form.

1. An average incidence of infection of 38 % was found in thirty-seven ring-neck pheasants over a period of 7 months.

2. There was a drop in the incidence from 70 % in October to 30 % in November. The incidence remained at 30 % during February and March and jumped to 67 % in April.

3. Three species of Eimeria were identified: E. phasiani Tyzzer and two new species, E. pacifica and E. megalostomata. A fourth type designated as type IV was seen but not described because of an insufficiency of specimens.

4. All infections observed were light. Histopathological studies showed little damage to the intestine and there was no significant difference between the weights of infected and non-infected birds.

5. Oocysts of E. pacifica sporulated at temperatures from 8 to 30.5° C. The latter is the optimum temperature. Intracellular organization prior to sporulation was indicated in oocysts of E. pacifica kept at 8° C.

6. A temperature of 37.5° C. was lethal to oocysts of E. pacifica. Degenerative changes in the oocysts were first observed 9 days after being placed at that temperature.

This work was done in the Zoology laboratory of Washington State College, Pullman, Washington. I wish to acknowledge my indebtedness to Dr R. F. MacLennan, of that Institution, for suggesting the problem, for his help and co-operation in the prosecution of the work, and to Dr F. S. Henika for assistance in the collection of specimens. I also wish to acknowledge my indebtedness to Dr Victor Burke and the Dairy Department for the use of the apparatus. Acknowledgement is also made to the Washington State Department of Game for permission to collect pheasants.