i6 Animal Life bv the Sea-shore. 



(if a black cokair, and terniinatm,;,' at both ends in a pair of 

 liorn-like processes, are known as " Mermaid's purses," and 

 are washed ashore empty after the escape of the j'oung. But 

 the eggs of tlie Dog-fish {Scyllimn) may be found attached to 

 weeds in sufficiently deep water not to be uncovered by the tide, 

 the attachment being by means of tendrils, of which the horns 

 of the Mermaid's purse are the basal remains. Such eggs are 

 here figured in outline. 



We cannot dismiss the fishes witlnAit saying a few words 

 about an extraordinary creature, the Lancelot or Araplrioxus 

 {Branchiosioma lanceolatmn), long placed in the class Pisces, 

 but now associated, in a division named Protochordata, mth 

 the Ascidians or sea-squiii;s, which will be dealt with in the 

 following chapter. It was first described, in the eighteenth 

 century, from a specimen obtained on the coast of Corn- 

 wall, and ma)iv \'ears elapsed before it was again rediscovered 



riG. I6, L,\NCELET. 



on our coast and elsewhere, it having a wide but very local 

 distribution in Europe. The Lancelet (Fig. i6) is a small, colour- 

 less, elongate, compressed creature, pointed at each end. two to 

 three inches long, without heart, in the ordinary- sense of the term, 

 ej'es or brain, or even cartilages, the axis of the body containing 

 .an elastic rod. kriown as the notochord, which in the develop- 

 ment of all vertebrate animals precedes the ^'ertebral column, 

 the vertebrae being formed above or around it. Curious tentacle- 

 like cirri form a fringe round its mouth, and were first taken for 

 respiratoiy filaments or gills, whence the misleading name 

 Branchiosioma, first proposed for it. It was not until 1866, 

 when the Russian zoologist. Kowalevsky, published the results 

 I if his researches on the development of the Lancelet and the 

 Ascidians, that a close relationship was shown to exist between 

 these two types, so different in appearance in their perfect 

 condition ; the Ascidians had until then been placed near the 

 Molluscs cir near the Worms. The Lancelet is not often met \vith 

 on our coasts, but ma)' be found in plenty in Jersej^ burrowing 

 in the sand in shallow water. It has even been found on the 

 shore at Polperro, not in a pool, but buried in a small quantitA' 



