100 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Millon’s reagent. When boiled with water for 30 hours the scales were almost com- 
pletely dissolved, and after 36 hours the undissolved residue was so small as to be 
negligible. The solution gave all the tests for gelatin. It gave also a strong biuret 
test, but not Adamkiewcz’s test. Nitric acid gave no yellow color or precipitate, but 
subsequent addition of ammonia caused a yellow coloration. The solution responded 
to the alkaloidal reagents, and gave Allen and Tankard’s 1 test for gelatin. No 
ichthylepidin is present. The organic matter of skate spines thus appears to be 
identical with that of the scales of the other elasmobranch fishes. 
Sun-fish (Mola mold ). — The integument was freed as far as possible from the 
subdermal collogenous tissue and treated with caustic soda, as before. The scales so 
isolated were washed thoroughly and extracted with HC1 as usual. They gave a 
strong Millon’s test, but no lead-alkali reaction. The decalcified and extracted scales 
were soluble in 5 per cent NaOH in 2d hours (differing from ichthylepidin, which 
remains unchanged for 5 days). 2 The decalcified scales were slowly but almost com- 
pletely soluble in boiling water, and after 3 days only a trace remained undissolved. 
The solution was concentrated but did not gelatinize, although it gave all the reactions 
of gelatin. The scales of Mold are thus analogous in composition to those of the 
elasmobranchs above noted, and are quite different from those of the higher fish with 
which it is classified. It is interesting to note in this connection the studies of Milne 
Edwards 3 and of Parker 4 on the vascular system of this species. Milne Edwards 
observed that in this fish “the coronary arteries are supplied not only from the 
fourth gill -arch as in other teleosts, but also from the third, fifth, and sixth arches, as 
in elasmobranchs.” Parker has confirmed this, and has shown also that the sun-fish 
has two coronary arteries, as is general in elasmobranchs. To quote Parker: 5 
This confirmation of Milne Edwards’s description shows that a really remarkable condition 
exists in the coronary arteries of the sun-fish. The presence of dorsal as well as of ventral coronaries, 
and the origin of the latter from more than one pair of visceral arches, are features so universally 
characteristic of elasmobranchs and so generally absent from teleosts that, while the sun-fish has most 
of the characteristic structural features of the latter, the arteries of its heart ally it unquestionably 
with the elasniobranchs. 
This is interesting, as the composition of the scales (exoskeleton) is also analogous 
to that of elasmobranch scales, and the morphological structure of the scale is also 
very similar. 6 
Puffer ( Spheroides maculatus ). — The skin of a puffer was removed, freed from 
adhering tissue, and treated with 5 per cent caustic soda. After 2 days the residue 
of star-shaped spines was washed thoroughly and decalcified with 5 per cent HC1 as 
above. The extracted scales gave no blackening with lead-alkali; Millon’s test was 
distinct. The decalcified scales were treated with boiling water to determine if the 
basis was all collogen or if ichthylepidin was present. After boiling 30 hours there 
was a small residue; whether this was ichthylepidin or not we were unable to decide. 
The solution gave all the reactions for gelatin. 
1 Allen, Commercial Organic Analysis (189S), vol. 4, p. 469. 
2 Morner, op. cit., p. 131. 
3 Milne Edwards (1858), Lemons sur la physiologic et 1'anatomie comparfie de l’homme et des animaux. Tome 3, p. 341- 
4 Parker. Note on the blood vessels of the heart in the sun-fish. Anatomischer Anzeiger, vol. 17, No. 16-17. 
5 Parker, op. cit., p. 315. 
6 Cf. Turner, Natural History Review (1862), p. 185. 
