CEPHALOCHORDA. 359 



in the vehi which is a sandy area of considerable size and with an average depth of from 

 6 to 7 fathoms. Five specimens were also brought up from a depth of 25 fathoms off 

 the west reef of the island, i.e. in the main lagoon of the atoll from a bottom of decaying 

 rock and sand. 



By far the largest number, however, came from a particular spot at the south end of the 

 velu, just to the north of the north-west point of Hulule island. From this end of the island a 

 sand spit runs out for a distance of some 70 yards, the greater part covered at low water. 

 The sand at the end of this spit suddenly dips down into a channel which at low tide 

 never had less than 4 feet of water in it. This channel was about 30 yards across its 

 widest part and ran east and west at right angles to the length of the island. At the 

 further end of the channel was another sand spit of about 50 yards breadth which gradually 

 sank into the velu. A current at almost all states of the tide ran up or down the channel, 

 often with considerable force, keeping the sand at the bottom and sides in a continual state 

 of motion, and it was in this sand that Asyirunetron was found to be most abundant. About 

 two hundred were actually obtained, but any quantity could have been caught if desired. 

 They were taken by wading out into the channel and dipping a sieve into the sand, a 

 dozen or more being often caught in one lot. 



It would thus appear that the chief and most favourable habitats are moderately shallow 

 and sandy channels, as in this place, in Fumadu, and in the channel in Minikoi, the three 

 places in which the greatest number were found. In all other places, where there was a 

 greater depth and an absence of current and sand, only a few odd specimens were taken. 

 There were several places visited in which the conditions seemed to be quite suitable for 

 Amphioxus but in which no specimens were found. This was notably the case off Goidu in 

 Goifurfehendu Atoll. The reason for this very local distribution is not easy to explain, but it 

 was noticeable that wherever Asymmetron was abundant, other sand-living animals were 

 absent or very scarce'. 



The distribution of this species from a larger point of view is interesting. Mr Crossland 

 obtained a few in Zanzibar, but no other specimens are recorded from the Indian Ocean. The 

 only other locality so far recorded is the Bahamas in the West Indies, where they were 

 first obtained by Andrews. 



2. Heteropleuron maldivense. 



The number of specimens found La the Maldives is too small to admit of any deduc- 

 tions as to habitat. Three specimens were found in Mahlosmadulu in coarse sand at a 

 depth of 20 fathoms, and one specimen in a channel into Fadifolu at a depth of 15 fathoms. 

 Mr Crossland, who found a large number of this species in Zanzibar, informs me that they 

 were taken on sandy bottoms at a depth of 7 to 8 fathoms. 



The following Cephalochorda have now been recorded from the Indian Ocean : — 



1. Amphioxus belcheri Gray. Madras, 6 fathoms, off " Seven Pagodas, Mahabili," dredged 

 by Major Alcock; and Singapore, several larvae and a few adults. This species also occurs in 

 Prince of Wales Island, Torres Straits and Borneo. 



2. Asymmetron lucayanum Andrews. Maldive Islands, Minikoi and Zanzibar. The species 

 is found also in the West Indies. 



1 In this couneotion it may be remarked that Asymmetron matter, and does not swallow sand, as do many other sand- 

 is a discriminate feeder. It lives on particles of vegetable living organisms. 



