264 TIDAL IRREGULARITIES. 
identical in some cases; in others closely allied to 
known species from Japan, Australia, and the 
shores of our own island. 
The tidal irregularities of this coast are per- 
fectly inexplicable. In May, June, and July, 
during the twenty-four hours, there is but one 
high and one low water. At the change and fall 
of the moon, high-tide happens near midnight, 
and varies but little as to time during these 
three months. In August, September, and Octo- 
ber there are two high and two low tides in the 
twenty-four hours. Then in the winter months 
(November, December, and January) the regular 
twelve-hour tides recur; but highwater is at 
twelve o’clock in the day, instead of twelve 
at night. The spring-tides range from ten to 
twelve feet, the neaps from five to eight. 
The temperature of the sea, taken during the 
summer months near the surface, ranges from 
52° to 56° F. The sea-water seldom, I may say 
never, looks clear, but always presents a turbid 
muddy appearance, as if a large quantity of sand 
was mixed with it. This may in some measure 
be accounted for by assuming that strong under- 
currents flow from north to south, and sweeping 
past the island, and being (from their low speci- 
fic gravity) close to the bottom, stir up sand and 
