61 



^Amphioxus), and many fragments of a small Fangia, which 

 must be very plentiful, but of which no perfect specimen was 

 obtained. 



Southward of the P^mban Pass are three islands, Pulli, 

 PuUivausel, and Coorisuddy, completely encircled by an 

 irregular coral reef, the whole forming a natural breakwater 

 protecting the pass and the channels leading to it from the 

 violence of the south-west winds. The space between the 

 northern edge of this reef and the pass forms a fine sheltered 

 anchorage for vessels of light draft in all weathers. The 

 deepest water between the above islands and the Pass is 

 immediately south of Coorisuddy, and is called the basin, over 

 which there is an average depth of 18 feet, but in one 

 spot there is a depth of 21 feet. This basin is, however, very 

 narrow, being simply a hole scoured out by the action of the 

 water in rushing through the pass : and, consequently, is of 

 little value to ships, as it has the pass to the northward of if. 

 with only 10 feet, and the sand-bank channel to the south- 

 ward with only 9| feet at low water. 



The tides are very irregular at Pdmban, the rise and fall 

 being much affected by the winds. The average springs rise 

 3 feet ; but, during neaps, sometimes for 48 hours, there is 

 frequently only a rise and fall of I or 2 inches. The 

 currents are generally influenced by, and strong in propor- 

 tion to the force of the wind. Thi-ough the Pdmban Pass 

 the current frequently attains to a velocity of from 5 to 6 

 knots an hour, rendering it at times difficult even to take 

 full-powered steamers through. During the north-east mon- 

 soon the current sets to the north through the pass. The only 

 months in which a real tidal carrent is noticeable are March, 

 April, and October, when it generally sets six hours each 

 way. 



No records of the temperature of the water over the reef 

 are extant, and, as my visits have always been at the same 

 season, extending over only a few weeks of the year, the 

 temperature observations which I have made are practically 

 of no value. The following table, however, shows the 

 maximum and minimum and monthly range, recorded at the 

 Pamban Marine office in the shade at 10 a.m. and 4 p.m. 

 during the twelve months from April 1st, 1888, to March Slst, 

 1 889. The range of temperature during that period will be 

 seen to be from 76^ to 92\ i.e., 16° :— 



