BIRDS OF ETHIOPIA AND KENYA COLONY 311 



4. R. c. cathemagmenus : Southern Kenya Colony from the Tsavo 

 district through the Taru Desert and the Serengeti Plains east of 

 Kilimanjaro to northern Ugogo in Tanganyika Territory. This race 

 differs from the first three in that the black gorget is not confined to 

 the females, but is present in the males as well. Females of this form 

 are very similar to those of hilgerti, but, like the males, have the 

 dorsum darker, more of a deep crimson-brown, than in hilgerti. 



Usually subspecies merge insensibly into each other at the periphery 

 of their respective ranges, and, consequently, when we find one that 

 does not, but maintains its distinctive characters in undiminished 

 strength to the very limits of its range, we may well wonder if it be 

 not more than subspecifically distinct. This is the case with cathe- 

 magmenus. Tlie males are strikingly different from those of any of 

 the other three forms, the black gorget being a large, well-developed 

 mark in this race and utterly absent in the others. It is worthy of 

 note that at the Tsavo station on the Uganda Railway hilgerti and 

 cathemagmenus meet, but specimens of both are wholly typical of 

 their respective races. It is true that the females of the two are very 

 similar, and, without their mates, are often extremely hard to identify. 



Recently, Hellmayr ^° has given examples among the Neotropical 

 avian family Formicariidae, of what he calls "heterogj^nism," which 

 term is intended to cover variations, both specific and subspecific, 

 which affect only the females, the males of the allied forms being 

 indistinguishable from each other. This is not peculiar to the For- 

 micariidae, as it is also known in some of the Icteridae, such as 

 the red-eyed cowbirds, Tangavius aeneus aeneus and T. a. involu- 

 cratus., and in some of the grackles as well. In Rhodophoneus^ how- 

 ever, the opposite is true; the males are very distinct and the fe- 

 males very similar (that is, in hilgerti and cathemagmenus)^ show- 

 ing that the difference in plumage may occur solely in either sex 

 and that it may be better to change Hellmayr's term to one covering all 

 cases where the difference is confined to one sex, regardless of which 

 one that is. 



All the seven specimens listed above are extremely abraded, and 

 two of them are molting in the tail and wings. As far as I have 

 been able to ascertain, nothing definite has been recorded of the 

 breeding season of this shrike, but it. probably is during May and 

 June. Thus, Blanford ^^ writes that this bird "was not rare around 

 Annesley Bay, and was occasionally seen in Samhar and Habab, up 

 to an elevation of about 3,000 feet, never, however, above the range 

 of tropical flora and fauna. In December and January small fami- 

 lies were met with, hopping along the ground, * * * jjj May 

 and June, all met with were in pairs." 



*• Journ. fiir Orn., 1929, Ergiinzungsband 2, Festschrift Ernst Hartert, pp. 41-70. 

 *^ Observations on the geology and zoology of Abyssinia, pp. 342-343, 1870. 



