424 



THE DIVING BIRDS — PYGOPODE.S. 



with those of the smaller specimens of occidentalis. In fact, examples occasionally occur which 

 may with equal propriety be referred to either species ; a majority, however, are typically one or 

 the other, the incompletely differentiated individuals forming a small minority. There is appar- 



ently no constant difference of coloration between the two, but Clarkii seems to have the lores more 

 often distinctly whitish than occidi ntalis. (See Henshaw, " Bull. Nutt. Orn. Club," Vol. VI. Oct. 

 1881, pp. 214-218.) 



It is not unlikely that the present bird may yet prove to be simply the female of JE. 

 occidentalis. 



This form, which bears a very strong resemblance to JE. occidentalis, was regarded 

 by Mr. Lawrence as being a distinct species, but is now considered as only a 

 variety. While it thus strongly resembles the occidentalis in size and in some of its 

 markings, it constantly differs. The two seem to have nearly the same habitat; and as 

 it is not usual for two races of the same species to dwell in exactly the same area, it 

 seems more probable either that the differences are specific, or that they possess some 

 sexual or other significance, unless the present form should be found to have a more 

 southern range. The first known specimen of this form was taken by Mr. J. H. 

 Clark in Chihuahua, Mexico, and other specimens were procured from the sea-coast 

 of California at Santa Barbara and on San Pueblo Bay. 



Dr. Cooper writes that near San Pedro, Cal., in July, 1863, he saw two large 

 Grebes, which he had no doubt were of this variety, frequenting the creeks and bays 

 for some months ; but they were so very shy, and seemed to know so well the range of 

 his gun, that he did not succeed in shooting one. He also saw large Grebes at Mon- 

 terey, after the 25th of September ; and as that is much earlier than the JE. occidentalis 

 is seen near the Columbia Kiver, he thinks that these also may have belonged to 

 this species. He observed nothing peculiar either in their habits or cries. Dr, 

 Heermann obtained one of these birds at Santa Barbara, which he referred to as 

 C. cristatus. 



This bird, as well as all the other species of Grebes, and also the Loons, have a 

 habit of gradually sinking into the water, until they entirely disappear, without leav- 

 ing a ripple on the surface. They can also swim with the head or the bill only just 

 above the water, and thus pass over a long distance without once being seen. One 

 of these birds was shot near San Francisco by Mr. Hepburn. Subsequently to 

 having made the above cited observations, Dr. Cooper writes that after a careful 

 examination of some specimens obtained by himself at San Pedro in 1865, it appears 

 to him doubtful whether the .E. occidentalis is not identical with jE. Clarkii. 



