Nearly a hundred heads had been found in this lake previous to Mr. Williams's explorations, and yet scarcely six skeletons. At first it is somewhat puzzling to account for this scarcity of skeletons compared with heads; but very likely the bodies, minus their heads, were carried right out of the lake, down a river, and perhaps reached the sea or got stranded somewhere down the river in such a way that the bones were never covered up. But in the Limerick bogs heads and skeletons were often found together. In that district the lakes were probably shallow and with but a feeble current, and so the body never floated away. This explanation by Mr. Williams seems satisfactory. He reports that the female skulls were rarely met with. Either they were more timid in swimming lakes, or, having no antlers, they may have succeeded in getting out, or the care of their young ones may have kept them out of the lakes during the summer months. The clay in which the remains occur is succeeded by another bed of pure clay, which _never_ yields any skulls or bones. This, Mr. Williams thinks, was deposited at a time when the climate was more or less severe, and the musk-ox, reindeer, and other arctic animals came down from more northern regions, even down to the south of France. He concludes that this period marks the extinction of the Great Deer in Ireland, whether rightly or wrongly it is hard to say. Many observers are inclined to think that it lived on to a later period. An interesting fact, having some bearing on the question, is this: that the bones in some cases even yet retain their marrow in the state of a fatty substance, which will burn with a clear lambent flame. Evidence such as this seems to point to a more recent date for its extinction. Steller's Sea-Cow.[80] [80] For fuller information, see the _Geological Magazine_, decade iii. vol. ii. p. 412. Paper by Dr. Henry Woodward, F.R.S. The Sirenia of the present day form a remarkable group of aquatic herbivorous animals, really quite distinct from the Cetacea (whales and dolphins), although sometimes erroneously classed with them. In the former group are the Dugong and the Manatee. These creatures pass their whole life in the water, inhabiting the shallow bogs, estuaries, and lagoons, and large rivers, but never venturing far away from the shore. They browse beneath the surface on aquatic plants, as the terrestrial herbivorous mammals feed upon the green pastures on land. Not a few of the tales of mermen and mermaids owe their origin to these creatures, as well as to seals, and even walruses. The Portuguese and Spaniards give the Manatee a name signifying "Woman-fish," and the Dutch call the Dugong the "Little Bearded Man." A very little imagination, and a memory only for the marvellous, doubtless sufficed to complete the metamorphosis of the half-woman, or man, half-fish, into a siren, a mermaid, or a merman. Hence the general name Sirenia.