88 DEPARTMENT OF THE NAVAL SERVICE 
7 GEORGE V, A. 1917 
a patch at the base of the pectoral fin also were discernible. Similarly four dark 
stripes were observed in a larger specimen of Gadus luscus (193 mm.) 72 inches long, 
described by Professor McIntosh. The first stripe occurred in the shoulder region, 
passing from the front of the first dorsal fin, and including its anterior third, and 
extending to the pectoral fin. The second stripe passed ventrally from a point anterior 
to the middle of the base of the second dorsal fin, while the third stripe, or belt, spread 
diagonally downward from the posterior third of the second dorsal fin to the ventral 
border of the turnk. Only traces were discernible of the fourth patch or stripe, on 
the surface of the caudal trunk near the base of the tail. 
What is the meaning of this phenomenon? How ean the occasional appearance of 
definite serial stripes or patches be accounted for, in species of fish and other animals 
in which normally they are absent? It would be interesting to trace out embryo- 
logically the development of a banded or barred arrangement in the external coloration 
of fishes, and to point out examples, discovered in recent years, of larval and post- 
larval arrangements of pigment in the integument; but in this paper the attempt will 
not be made, and a few salient points alone will be set forth. Most people familiar 
with our common food fishes have asked the question, “What is the explanation of the 
black thumb-mark on the shoulder of the haddock?” Why do not closely related fishes 
such as the cod, pollock, and other species, exhibit similar dark patches or spots? The 
English whiting (Gadus merlangus) does show a patch of black at the base of the 
pectoral fin or rather in the axil of the fin, and the post-larval stage 14-inch (28 mm.) 
long, shows thirteen or more spots or partial stripes of black along the dorsum, as 
Professor McIntosh has described and figured, 4, p. 17, vide Plate IX., fig. 5. Dr. 
Gunther pointed out (2, p. 540) that in Greenland, Iceland, and Northern Scandinavia, 
the common cod exhibits a large irregular blotch of black pigment on the side; but the 
absence of striking dark patches in species closely related, as just stated, can only be 
explained on the ground that such stripes are of little utility, and that a barred 
coloration is not essential to the welfare of the fish. There are many living creatures 
to which a patched or banded condition appears to be of vital importance. Spots and — 
stripes have been proved to be of value for protective purposes, especially for conceal- 
ment, but such purposes cannot be served by the presence of dark bands along the body 
in the haddock or bib, and any key to the origin and meaning of such coloration must 
be sought more remotely. There can be little doubt that the significance of these serial 
stripes is ancestral. Beddard called attention to the fact (6, p. 19) that among 
segmented creatures, like worms, caterpillars, ete., we find a pattern of coloration con- 
forming exactly to the segmentation of the body. Rings of colour correspond to the 
rings of the body. Now, in their earliest larval condition young fishes have a long 
eylindrical body, like a worm or eel, and it shows division into segments or serial body- 
rings, called metameres. May it not be the case that the bars or serial patches of 
colour primitively correspond to the muscle-segments, the myotomes or metameres ?* 
If a segmented body be typical of the ancestral form of animals, there is strong pre- 
sumption that repeated spots and stripes along the surface of the body may be ancestral 
also. As I ventured to point out in a paper on this subject of “Animal Coloration” 
(7, pp. 154-155): “In some flat fishes the bars along the sides of the body divide into 
spots or large patches, four rows of them, and still preserving their metamerie or serial 
succession from the head to the tail. Thus from successive cross-stripes the spots 
arise, and these surface arrangements of colour continue long after the internal organs, 
the muscles, etc., have wholly altered their original anatomical arrangement. Further, 
the successive series of spots may unite later as longitudinal stripes, and such stripes 
we find in the post-larval ling (Molva).” We have thus a key to the arrangement of 
*The late Professor J. A. Ryder said (Embryography of Osseous Fishes, U.S. Fish Comm. 
Rep. 1882, Washington, 1884, p. 502): “The pigment cells are stellate, and exhibit a slow 
amoeboid or migratory movement as development proceeds, becoming aggregated at a later 
period by this means into patches upon definite regions of the body.” 
