162 CALIFORNIA ACADEMY OF SCIENCES. 



be a development towards a uniform pigmentation of 

 each feather. 



The subject of the lines of pigmental development 

 has received more, attention at the hands of the Ger- 

 man scientists than from any others.* The re- 

 searches of Eimer in particular are in accordance with 

 the view here stated. It seems that among nearly 

 all animals (at least among the vertebrates), the earl- 

 iest form of color is the longitudinal streak. These 

 longitudinal markings are finally broken up into spots 

 (when the tendency to assume a uniform color does not 

 assert itself) and the spots ultimately fuse into cross 

 bars. 



This view of the general succession of patterns has 

 been commonly accepted, although denied by Kerschner, 

 who asserts that the longitudinal barring is the oldest 

 form of marking. As his conclusions were based upon 

 a limited number of forms, the eye spots of the pea- 

 cock's tail having claimed his special attention, they 

 cannot be considered to be of general validity. Hacker 

 has devoted special attention to pigmentation in the 

 thrush family, although he considers the water birds 

 also to a certain extent in the paper cited below. With 

 the exception of the primitive streak he finds the clear 

 feather with a pigmented border to be the earliest form, 

 which may be modified into a spot as in the thrushes. 

 The coloring of the interior of the feather he considers 

 to be due to a secondary pigmentation. 



* Ou this subject SQe Tli. Eimer, Uutersnchnngen iiber das Variireu der 

 Mauereidechse, etc., 1881. Ueber die Zeichutiugder Vogel iiud Siiugethiere. 

 Jaresliefte des Vereius fiir vaterld. Natiirk. iu Wurttemberg, 1883, p. 

 556. Zoolog. Auzeiger, 1882-83. Humboldt, 1885-1887. 



Dr. Kerschner, Ziir Zeichnung der Vogelfederu, in: Arbeiten aus dem 

 Zoologischen Institut zu Graz, I. Band, Nr. 4. Leipzig, 1886. 



V. Hacker, Unter uichungen iiber die Zeichnimg de Vogelfedern. Zool. 

 Jabrb., Ill, Jan. 15, 1888, pp. 309-316. 



