The generic characters of Eumacronychia are reviewed and as here considered the genus includes 21 nominal forms of which 9 are described as new. All members are quite similar in habitus and difficult to distinguish except by reference to the male terminalia. A key to all known species is included to facilitate identification. The maximum distribution of the genus is centered in the southwestern United States with the present known extreme range extending from Canada to Guatamala.

No abstract

No abstract

The new genera and species described below are based upon material collected largely in the western United States and Canada. The types represented by Canadian material, which was loaned for study through the courtesy of A. R. Brooks, are returned to the National Collection at Ottawa. Unless otherwise specified under the descriptions, the remainder of the type specimens are in my collection.

Spontaneous behavioral categories such as attack. submission. boxing. allogrooming, mounting. and anogenital control were investigated in nine groups of three rats each. At the same time. the number of wins in the runway test and the amount of time spent occupying access-to-water space were registered in competitive tests. Antagonistic behavior jattack and induction of submission) permitted no significant relationships to be drawn as to the results of the competitive tests. The competitive parameters. too. showed no correlation among themselves. In agreement with other authors. we reject the existence of an encompassing unidimensional rank order in rats on the basis of these results. Attack wins and induction of submission showed a positive correlation to one another as well as to relative thymus and testes weights. A high antagonistic activity was also correlated with low relative adrenal weight. large number of nuclei in the adrenal cortex. and wide tubuli seminiferi in the testes. As indicated by factor analysis. a significant decrease in body weight. low heart. thymus. liver. spleen. kidney. and testes weights. and high adrenal weight with decreased number of nuclei in the adrenal cortex were typical for rats with low aggressive rank positions. The influence of endocrine organs and diminished physical vitality in these low-ranking animals was also observed following nonsocial stress.