196 MADRAS FISHERIES BULLETIN VOL. XIV, 



A smaller species is found at Tuticorin, its valves washed 

 ashore in great quantity after storms. This also appears to live in 

 stiff peaty deposits, such as are formed by the consolidation of 

 old sea-grass beds. It is also common at Calicut. 



In floating timber, other Borers of this family are found ; a 

 common Indian species is Pholas {Martesia) striata. 



The Ship-worms {Tercdinidac) are still more specialized for 

 boring, but they confine their attention entirely to wood. The 

 body is long and worm-like, the siphonal tube being of extra- 

 ordinary length, united through the greater part of its course. The 

 shell is small and globular, covering only the thick anterior end. 

 where the visceral organs are situated. The tiny valves show 

 resemblance in essential features with those of the Pholads, espe- 

 cially in the presence of a calcareous " spur " in each umbonar 

 cavity ; Teredo has evidently descended from a Pholas-like 

 ancestor, suffering extreme modification in its successful attempt to 

 perfect its form to a burrowing habit. The body of some of the 

 common species may reach a length of a couple of feet or more 

 with a diameter of about a quarter of an inch. As it starts making 

 its burrow when quite tiny and never quits it, the aperture to the 

 exterior is minute. The burrow is lined by a calcareous tube, not 

 connected in any way with the body of the Teredo, but deposited 

 from a secretion poured out by certain glands. Ship-worms 

 are extremely destructive to timber, especially in the tropics ; 

 unless protected by sheathing, woodwork under water becomes 

 riddled with the multitude of their burrows within a few months. 

 The hardest wood is not immune. I have seen ironwood piles 

 completely destroyed, reduced to a mere shell of honeycombing, at 

 Tuticorin. Dealwood perishes within a few weeks. Their ravages 

 cause constant anxiety to the owners of small coasting craft and 

 fishing canoes ; the old Indian method of combating the ship- 

 worm is to haul the boat ashore or else to careen her, and after 

 drying as thoroughly as possible to daub the under-water parts 

 with a mixture of chunam, dammar and oil. Canoes being easier to 

 handle are frequently hauled ashore, dried, and the bottom 

 smeared with rancid fish-oil, of an odour warranted strong enough 

 to disgust any ship-worm that comes near. 



A short length of the siphon tubes is free at the hinder end and 

 at the point of junction of these free ends with the long united 

 siphonal region, are situated a pair of tiny palette-like limy plates 



