Sie ee go 
- Mar. 13, 1873] 
ankle, as in Megalonyx and the other allies of Megathe- 
rium, was not pivoted as in the sloths, but the inner ma- 
leolus was quite cut away and replaced by a slightly con- 
cave articular surface looking downwards and a little 
inwards, which was continuous with that of the lower 
ends of the tibia, aridge intervening. The superior surface 
of the astragalus was consequently of a peculiar form, 
possessing a longitudinal median groove. The first and 
second digits of the foot were missing, and a claw was 
present only on the third, in which the middle and distal 
phalanges were anchylosed ; there were two phalanges on 
the fourth toe, and only one was present on the fifth. 
As to its habits, there is no doubt that Megatherium was 
not a burrower as supposed by Pander, nor arboreal as 
suggested by Lund, but that Prof. Owen’s hypothesis is 
correct in which he considers that it was terrestrial, feed- 
ing on trees, which it uprooted or broke boughs off. 
Mylodon possessed the same number of teeth as its 
allies and the sloths, but the anterior pair in the upper 
jaw were separated by a considerable interval from those 
behind. All the teeth were more or less cylindrical and 
had persistent pulps ; the worn surfaces were cupped and 
not ridged, because the dentine was softest in the cen- 
tre ; the fourth lower molar was elongated and grooved. 
Several species of this genus have been found, one only in 
North America. Gervais has divided off some with more 
separated anterior molars into a new genus, but Burmeister 
does not think this justifiable. The College of Surgeons 
sesses a very good skeleton, almost perfect, obtained 
in 1841. The skull was very slothlike, the fore part being 
truncated and the nasal fossae open. There was a large 
descending process of the zygoma and an ascending one ; 
the bony arch was complete. There was no enlargement 
of the molar region in the lower jaw like that of Mega- 
therium. Air cavities existed all round the brain-case, as 
in the elephant, but to a less degree The vertebrae were 
C. 7, D. 16, L. 3, S. 7, and Caud. 21. The lumbar ver- 
tebrz were anchylosed together to the last dorsal and to 
the sacrum. The tail was long and powerful ; the limbs 
much like those of Megatherium, but differed in the radius 
and ulna being separate, as were the tibia and fibula. In 
the fore-foot Mylodon had the five digits, with claws. 
on the first three, The ankle was as in Megatherium ; 
the hallux only was missing, and the fourth and fifth toes 
did not carry claws. : 
Scelidotherium was smaller and altogether lighter built 
than those mentioned above ; the teeth were equidistant 
and elongated from before backwards as was the head. 
The rest of the skeleton much resembled Mylodon, but 
the lumbar vertebrae were not anchylosed. 
Megalonyx was a North American form, Prof. Leidy 
has described it fully. There was a great gap between 
the anterior tooth, which was large and much like a 
canine, and the other molars, whose number were the 
same as in the sloths. The animal had longer and 
slenderer limbs than those described above and therefore 
more nearly approached the sloths. 
{In last week’s report of these lectures, Thy/acoleo is 
misprinted Z/y/acoles, and the animal is stated to have 
32 instead of 2 molar teeth in the lower jaw.] 
FAUNA OF THE NEW ENGLAND COAST 
peor. VERRILL, in discussing the collections made 
by the parties of the United States Commis- 
sioner of Fish and Fisheries upon the Coast Survey steamer 
Bache during her cruise off the coast of New England, in 
the summer of 1872, sums up by stating that they repre- 
sent six distinct faunas and sub-faunas as follows :— 
(1) The surtace fauna outside of the banks, and, at 
certain times, even extending over their outer slopes. 
This is essentially the same as the fauna prevailing over 
the entire surface of the central parts of the Atlantic 
NATURE 
. 365 
Ocean, and shows very clearly the direct effects of the 
Gulf Stream. 
(2) The surface fauna inside of the Banks, which is 
decidedly northern in character, very similar to that of 
the Bay of Fundy. The contrast between the two shows 
that the Gulf Stream is almost entirely turned aside by 
the Banks, and has comparatively little effect upon the 
fauna between them and the coast. 
(3) The fauna of the St. George’s Bank: itself. This is 
decidedly boreal in character, and essentially identical 
with that of the Bay of Fundy at corresponding depths, 
on similar bottoms, and in regions swept by strong 
currents. The fauna of the south-western part, however, 
is less boreal than that of the north-western. 
(4) The fauna of the Le Have Banks, and off Halifax. 
This, even at the moderate depth of twenty fathoms, is 
decidedly more arctic in character than that of the St. 
George’s or the Bay of Fundy at similar or even greater 
depths. 
(5) Between the St. George’s and Le Have Banks and 
the coast there is a great region of cold and comparatively 
deep water—in places more than 100 fathoms in depth— 
with a bottom of mud and fine sand, and communicating 
with the great ocean-basin by a channel between the 
St. George’s and Le Have banks, which is comparatively 
narrow and, in some places, at least 150 fathoms deep. 
This partially inclosed region has, physically and zoo- 
logically, the essential features of a gulf, and may be 
called the St. George’s Gulf. The deeper waters of the 
Bay of Fundy are directly continuous with those of this 
area. The fauna of this Gulf and of its outlet is pecu- 
liarly rich in species new to the American coast, and nearly 
identical with that of the deeper waters of the Gulf of 
St. Lawrence, arid agrees very closely with that found on 
muddy bottoms, and at similar depths, on the coasts of 
Greenland, Finmark, and Norway. 
Healso presents additional generalisations as follows :— 
(6) The deepest dredging, in 430 fathoms, was outside 
of the St. George’s Banks, on the slope of the actual 
continental border, and within the limits of the true 
Atlantic “basin.” The fauna there is especially rich and 
varied, decidedly northern in character, and agrees 
closely with that of similar localities and depths on the 
European side. The animals were mostly such as 
inhabit bottoms swept by strong currents in the Bay 
of Fundy. : 
(7) Everywhere over the banks, and especially on the 
southern slopes, the difference between the bottom and 
surface amounts to from 15° to 20, or even more; the 
surface temperature being usually from 60° to 72°. The 
temperature of the air was very near that of the water, 
generally one or two degrees higher. 
(8) Nosuch contrast of temperature was found inside ot 
the Banks in the St. George’s Gulf or the Bay of Fundy ; 
the difference seldom being more than ten degrees, and 
often, especially in the Bay of Fundy, less than five. 
The surface temperature at corresponding dates in the 
Bay of Fundy were 48° to 53°, showing an average 
difference of about 20° for the surface temperature in the 
two regions, while the average bottom temperatures do 
not appear to differ materially. : 
(9) The high surface temperature of the Banks is 
evidently due chiefly to the direct influence of the Gulf 
Stream. 
(10) The very low surface temperature of the Bay of 
Fundy is largely due to its geographical position, and the 
absence of any appreciable influence from the Gulf 
Stream, but it is no doubt intensified by the powerful 
tides, which are constantly mixing the cold bottom water 
with that of the surface. 
The facts hitherto observed do not seem to warrant 
the assumption that an “arctic current,” properly so- 
called, as distinguished from the tidal currents, enters the 
St. George’s Gulf or the Bay of Fundy. ‘The action of 
