On the north-east coast of Yezo, where pits are found, some Ainu huts have round and others angular roofs; but even in the latter instance, the angle of the two sides of the roof is not as acute as with the huts on the Saru and the Tokachi River; but both slant in a more gentle way, forming an obtuse angle of about 135°. In fact, these variations in the Ainu architecture have not yet been accounted for, and whether they copied their roofs from their foes the Koro-pok-kuru, or whether it is a mere chance that the roofs bear a certain resemblance, cannot be discovered from tradition or hearsay. I may mention incidentally my own theory, which may afford an explanation of this point. As the Saru, the Tokachi, and the Ishikari districts have no very severe weather in winter, and only a comparatively small quantity of snow falls during the colder months, the Ainu build huts with very slanting roofs, so that the snow should not remain on them in winter, while during the summer months the rain should fall off the steep incline of the roof before it could filter through into the hut. On the Kutcharo Lake and on the north-east coast, where strong winds are prevalent, the huts have round roofs, so as to offer the least possible resistance to the gales, and thus escape the danger of being blown down.
With regard to the snow, the opposite of the Saru Ainu method is practised. Instead of preventing the snow from resting on their roofs, the Ainu of the colder regions do all they can to let it remain, for by thus forming an air-tight vault it renders the hut much warmer in winter. In other words, the system is the same as that adopted by the Esquimaux, with the exception that the latter, I believe, have no frame to their huts, and the vault is entirely of snow and ice; while with the Ainu of the north-east coast the snow vault is directly over the hut itself. I invariably noticed on the north-east coast, where the Ainu have a mixed architecture, that wherever a hut was built in an exposed position it had a round roof, while those built under the shelter of a cliff or a hill had angular ones, and this is what led me to the above conclusion.
To return to the Koro-pok-kuru, they undoubtedly must have had semi-spherical and semi-cylindrical roofs over their pits, whether the vault was constructed of mud, sticks, and reeds, or simply of snow and ice, like the Esquimaux dwellings. For all that we know, the Koro-pok-kuru huts may have had conical roofs, like those of the present American Indians; but one fact is certain, that whatever shape the roof may have had, it was not supported by a central pole, for the hearth is invariably in the centre of the pit.
The curious fact already mentioned, that in every pit we find a thick layer of sand, seems to prove that it was certainly intended to render the ground less damp; and it is my own impression that these pit-dwellers, having snow or ice vaults over their heads, resorted to that expedient to keep the floor of their huts dry under the continuous dripping of the vault, melted by the heat of the fire inside. Undoubtedly Yezo was a much colder country in bygone years than it is now; and though we cannot implicitly rely on the information given by the Ainu, they are all of one opinion in believing that their country was all ice and snow in former days, and to give a proof of it they say: "Why should we be as hairy as a bear if not to keep the cold out?"
The Japanese know the pit-dwellers by the name of "Ko-bito," or "Ko-shto," the latter word meaning "men of the lakes,"[28] but they know nothing of their history.
One fact still remains to be explained, namely, who made the pottery that is disinterred in almost every pit and by the shores of lakes. The present Ainu do not know how to make pottery, and they have never been known to manufacture anything of the kind. All Ainu implements are made of wood, though of course the more civilised tribes have now purchased iron or porcelain implements from the Japanese. The question, then, is, supposing that the Ainu were formerly the pit-dwellers, have they lost the art of making pottery, or did the pottery belong to a different race of people?
KORO-POK-KURU POTTERY AND FRAGMENTS OF DESIGNS.
It seemed singular to me that, conservative as the Ainu are of their relics, even allowing for its brittle nature, no pottery of the kind found in pits is ever to be seen in any Ainu hut. Had they made the pottery themselves, surely some specimens or parts of specimens would have been preserved.
Comparing facts, we find, then, that the Koro-pok-kuru built their huts over pits, made pottery, and used stone and flint implements; while the Ainu have never been known to dwell in pits, have never made pottery, and have always used bone or bamboo implements. Moreover, Ainu traditions of internecine wars, vague as they are, and their designating the enemy by the name of Koro-pok-kuru, are further proofs that the Ainu themselves do not regard the pit-dwellers as their forefathers. As, then, the few facts collected tend to prove that the Ainu and the Koro-pok-kuru were two distinct races, it would be interesting to know who the latter really were, and what became of them. A learned missionary, Mr. Batchelor, writing on this subject, says:—"But I am of opinion that these pit-dwellers were closely allied to the Ainu in descent, and that the remains of them may now be seen in Shikotan and other islands of the Kurile Group. The inhabitants of Shikotan are much shorter in stature than the Ainu of Yezo. They are not so good-looking, and are said to be a very improvident race. The Ainu look upon the Kurile Islanders as the remnants of the Koro-pok-gurus; but this is a mere opinion, to be adopted or rejected at pleasure. That they are pit-dwellers is quite certain, for they live in pits at the present day."