THE WORMS 71 



within sand}' heaclies in tuhnlar l)nrrows lined Avitli mucous, and 

 the situation of the barrow is ahvays marked by a heap of coiled 

 string-like masses ol sand cast out at its mouth. The creature is 

 about five inches long and so delicate that its own weight is suffi- 

 cient to break it into pieces, so that it must be dug and washed out 

 of the sand with great care. The front end of the body is, how- 

 ever, quite tough and muscular, and is elongate and acorn-like in 

 shape; although it is often expamJed and contracted in life. Back 

 of this acorn there is a thickened, collar-like region, and then comes 

 the long, tapering, worin-shaped body. The acorn is usually yellow 

 or dull orange, the collar darker orange, and the body greenish- 

 brown or brownish-purple, often mottled with dull white spots. 

 The mouth is at the lower front edge of the collar, and the creature 

 f.'eds upon the minute organisms contained in the large quantities 

 of sand which it swallows. The intestine extends straight through 

 the body. The sides of the intestine in the forward part of the 

 body are pierced, however, bj' numerous gill clefts which open to 

 the outside in a series of pores along liotli sides of the middle of the 

 back. Now, gill slits are peculiar to tlie vertebrates, being found 

 either in embryonic or adidt life in every known vertel)rate from 

 the lowest lislies up to man. Indeed, many naturalists have sup- 

 posed that B(i]avogli'y>:iis might l)e a survivor of the ancient race 

 \\diich long ago gave rise to the vertebrates. On the other hand the 

 larva of Bahinoglof!>:ii!^ is free-swimming, and bears such a remarkable 

 resemblance to that of a starfish, nr Echinoderin, that no one sus- 

 pected it to be anything else until it was reared and oljserved to 

 change into a Bahnioiilossii.^. It is ])ossible, therefore, that BaJann- 

 (//ij.s.s(/.s is descended remotely from ancient forms which gave rise 

 to both the annelid worms and the Echinoderms. The discussion 

 of tliis interesting subject would, however, take us too far afiekl, 

 and the reader is referred to the table of references for further 

 accounts of this si^ecies. 



