This and the following 13 papers, numbers 10 to 23 inclusive, form the bulk of the report of the Hospital and Laboratory of the New York Zoological Park for 1938. A few papers were received too late for inclusion in Part 3 of Zoologica and will be published in Part 4. This particular paper is a resume of the causes of death in the collection and employs the titles of the International Classification of Causes of Death (human) adopted by an international commission in 1929. Necessarily some of

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... e titles have been modified to include specific animal diseases not encountered in human medicine and to exclude certain diseases of humans to which animal populations have native immunity. It has been suggested that joint causes of death be used, and this practice is attempted here with precedence given to those conditions which we believe were primary. In the (unfortunately) rare instances in which mortality statistics of zoological gardens have been reported in the past, stress has often been laid upon percentages of mortality. This device has been eliminated from the present report because it is believed that percentages are all too likely to give a false interpretation of the actual state of the collection. Animals in zoological gardens fall into two main groups: the immature (juvenile or pre-adult), and mature (adult). Finer distinctions may sometimes be made, particularly in the Mammalia, but even here accuracy is frequently problematical unless ages are positively known, as when an animal has been born in captivity. Consequently we may find that we have a community populated with individuals the majority of which have reached the upper limit of life expectancy -with the result that in any one year the mortality percentage may rise abruptly with no real cause other than a shift in the average age of the exhibits. At this stage of-zoological knowledge, no reliable criterion is available for age determination in birds and reptiles, and they are therefore listed here simply as immature or adult. Mammals have been classified as immature or pre-adult, adult and post-adult or senile, except where specific ages are known. Longevity records of exhibition life are, of course, available, but the age of newly acquired specimens is seldom accurately known. To prevent the complication of this table beyond easy interpretation, we have not divided the exhibits into groups below Orders. The table will be found to state the postmortem reference number as carried in the records of the Hospital and Laboratory of the New York Zoological Park. Preceding the table is presented a list of specimens in numerical sequence, grouped by Classes, which will identify each by common and scientific name. hov 8 im 266 Zoologica: New York Zoological Society [XXIV :10 Anyone interested in specific postmortem reports may apply directly to the Hospital and Laboratory, citing the postmortem reference numbers. For example, the first item in the table lists, under selected causes of death, No. 1, typhoid, one immature member of the Squamata, R-26-38. R refers to reptiles; 26 is the 26th postmortem conducted on a reptile; 38 refers to the year 1938. Our reference list identifies the specimen as a South American boa, Constrictor c. constrictor. Our laboratory record cites the organism recovered, together with sugar reactions and final serologic identification, 4 plus agglutination against a specific Eberthella typhosa antiserum, in a dilution of 1 :640. To take another example, the adult member of the Carnivora M-155-38, listed under selected causes as 46F, cancer of the pancreas. The reference list preceding the table reports M-155-38 as a Kadiak bear, Ursus middendorffi. In this instance a report is currently published, as paper number 11 in this series. Where especially interesting cases were studied in detail, either by members of the staff or specialists, reports are published in this and other journals. For the greater mass of material, however, it seemed moi'e advantageous to give a titled summary as in the table that follows, with reference numbers that would enable anyone interested to obtain full information by applying to the laboratory of the Zoological Park, rather than to attempt here a detailed report that would necessarily be almost interminable. It remains only to be noted that many specimens in our permanent records originated outside the Zoological Park and are not, therefore, included in this statistical summary, and that not all specimens, in the collections, that died during the year were sent to the laboratory for examination.