196 



KNOWLEDGE. 



[Septembek 1, 1898. 



means will be found for making models of the bottle-nose 

 Hyperoodon and of one of the beaked whales, the latter of 

 which are now represented in the gallery by a series of 

 skulls. 



Apart from a couple of porpoises, the models in the 

 dolphin family include those of the kUler and the white 

 whale ; the former species being remarkable for its bold 

 alternation of light and dark colours, while the latter is 

 unique on account of the pure creamy white hue of its 

 glistening skin. Why the white whale should have a hide 

 of this bridal hue, while its not very distant relation the 

 pilot-whale (Glohicephalus) is clad in deep sable, stands 

 urgently in need of explanation. A model of the latter 

 species is shortly to be added to the gallery ; and, both on 

 account of the spotted coloration of its skin and the 

 peculiar conformation of the head, one of the narwhal 

 would also prove an interesting addition to the series. 



In the vestibule of the new gallery is a small case 

 containing representatives of the small family of freshwater 

 dolphins (Platiuiistichh), the few living types of which are all 

 creatures of comparatively small size. While the Indian 

 susu (Platanista) is represented chiefly by skeletons and 

 skulls, of the La Plata dolphin (Pontoporia) the plaster 

 model of a specimen killed during my first visit to 

 Argentina forms an attractive exhibit. Its peculiar light 

 brown colour seems to have been produced to harmonize 

 with the clear, but brown-stained waters of the Kiver Plate. 



Till the new gallery was opened the Cetacean collection 

 of the Museum was exhibited in a low, ill-Ughted, and 

 crowded gaUery, where the incautious visitor was only too 

 likely to run the risk of cracking his own skull against 

 that of a whale, and where skeletons alone formed by far 

 the greater portion of the show. That gallery is now 

 closed to the public, but the contrast between its dismal 

 array of bones — almost unmeaning to all save the 

 anatomist — and the present light and interesting exhibition 

 will probably survive in the memory of some of my readers. 

 In a word, while the old style was exactly what a museum 

 ought not to be, the modern one is precisely what it 

 should be. 



REPETITION AND EVOLUTION IN BIRD-SONG. 



By Chakles A. Witchell. 



THROUGHOUT the animal world we may find 

 numberless instances of acts being rapidly repeated, 

 with apparently only one sustained effort for the 

 series, which acts seem to have originaUy been 

 performed much less speedily and with separate 

 efforts. Repetition means facility. Facility generally 

 implies rapidity of repetition, and a series of acts for one 

 purpose. 



In the cries and songs of birds, we not only find indica- 

 tions of a former progressive evolution through the 

 medium of mere repetition, but we may observe this 

 evolution in actual development. I have elsewhere sug- 

 gested that some prolonged alarms and songs of birds may 

 be considered to have been evolved from mere repetitions 

 of one cry. We may suppose that in some species a long 

 song was a desideratum, since it is unaccompanied by any 

 considerable variation in pitch. In the night-jar and grass- 

 hopper warbler there is practically no variation, though 

 the latter " drums " in about the interval of a minor third. 

 The cricket-like chirp of the chiff-chaflf may be heard 

 everywhere, and is occasionally given in autumn as well 

 as in spring ; but I have never heard it rendered in more 

 than three syllables ; and it almost invariably consists of 

 two only. It would be interesting to know whether readers 



of KNo^^^:,EDGE have ever heard this uttered with four or 

 five syllables. If such a local variation were discovered 

 it might be considered as a survival of an earlier form of 

 cry, or as an advance upon the ordinary song. I incline 

 to the former proposition. 



The turtle dove has a tremulous purring note, reminding 

 one of the croak of the common frog (not of the more 

 commonly heard " work, work" of the toad). It seems to 

 consist of a very rapid succession of little coos. If greatly 

 prolonged it would remind one of the note of the night-jar. 

 In the common pigeon, and some of the doves also, a 

 succession of little coos constitutes the whole song, which 

 is often somewhat elaborate — as in the common coUared 

 turtle dove. 



There may, of course, be the change of retrogression or 

 reversal, as well as changes due to elaboration. The 

 great titmouse seems to afford an instance of the former. 

 The young (out of the nest) have a repeated cry with a 

 curious wryneck-like tone, which may be rendered " klee, 

 klee, klee." It is generally repeated from three to five 

 times. The old bird never repeats a cry of this tone, but 

 it utters a long single note as a cry of distress when a 

 hawk is in sight. The cry of the young is no doubt 

 inherited, and it may seem that the note may formerly 

 have been repeated often by adult birds where it is now 

 given only in single long cries. 



On the other band, the adult great tit has an alarm (a 

 rapid " shashashasha ') which is absent from the young. 

 This is the most frequent danger signal of the old birds, 

 and it always contains many syllables, all given, however, 

 at the same pitch. How long it takes a wild titmouse to 

 develop a variation of an alarm cry I know not, but in 

 Western Canada I heard the marsh tits giving precisely the 

 same note as their British prototypes, though the birds of 

 the two countries must have been whoUy separated during 

 an incalculable period of time. 



At Montreal, also, the house-sparrows (which were said 

 to have been introduced fifteen years earlier from the States 

 and not from England), had exactly the same cry, as well 

 as the same manners, as the British bird. The sparrow, 

 when bred in a cage, proves itself to have a strong tendency 

 towards mimicry ; yet these Canadian birds, like the marsh 

 tits in the Far West, and the sparrows that chirp on the 

 Bank of England, retained the ancestral tones of their 

 species. 



An interesting instance of repetition, developed in one 

 strain to completeness, and in another not advanced beyond 

 an elementary stage, occurs in the wood-wren. This bird's 

 song consists of the simple repetition of a not musical 

 sound, slow at first, but gradually getting faster until the 

 song ends in an ecstasy. The whole may be rendered 

 " si-si-si-sisisisisi." The pitch varies only a little : but 

 there is a beautifully even accclerdndd in the strain. The 

 bird has another cry which might be taken for a song, 

 but this seems to be really a signal of danger. It is a full 

 brief whistle repeated two or three times at the same pitch, 

 and at about the rate of two per second. It may be written 

 " kew, kew, kew." I have listened, but in vain, for any 

 sign that even one of these birds had any inclination to 

 repeat this beautiful note more than four times in succession. 

 If that sound were somewhat prolonged, and given a few 

 more times, it would rival some of the sweetest strains of 

 the nightingale. But the wood-wren neglects this pure 

 tone, and throws all his effort into the sibilous strain which 

 falls to us from the tree tops, even as it fell on the ear of 

 Gilbert White long ago. 



The cuckoo, like the wood-wren, has developed the 

 repetition of a note into a strain — a full-toned bubbling 

 cry which is uttered at least by the female — yet the well- 



