CLAVELINA. 27 



body, which is closed at the extremity, is at first simple, but rami- 

 fies as it elongates. When its growth is more advanced, we see 

 developing at the extremities of its branches, or even at different 

 points of its length, tubercles containing in their interior a little 

 organised mass in connexion with the internal tube. These tu- 

 bercles elongate, elevate themselves vertically, and become clavi- 

 form ; the blood which circulates in the stem penetrates the soft and 

 pyriform central mass; but this mass, at first pedunculated and 

 adhering to the inner tunic of the principal canal, soon separates 

 itself, and no longer participates in the circulation of the indivi- 

 dual to which it owed its origin. Nevertheless, its development 

 continues, and we soon distinguish in it all the principal charac- 

 teristic traits of Ascidian structure; the branchial sac becomes 

 perfectly outlined without being as yet in communication with the 

 interior; a curved digestive tube is seen beneath the thorax. At 

 length a buccal opening is formed, and the general shape of the 

 young animal approaches more and more nearly that of the adult. 

 Thus there is produced, by process of budding, a new individual, 

 linked with its parent by a radiciform prolongation of the tegu- 

 mentary tunic, and which, during the first years of its life, has a 

 circulation in common with the mother-ascidian, but in the end 

 enjoys an independent existence. Still, however, it may remain 

 in connexion with the individual which produced it, through the 

 medium of its roots, or it may become completely free by their 

 rupture, without any change of consequence in its mode of life." 

 (Memoires de I'lnstitut, vol. xviii. p. 2G2.) 



In the memoir cited, Milne-Edwards has distinguished 

 several species of Clavelina^ most of which arc likely to 

 occur on our coast. One is the Clavelina Savigniana, the 

 abdominal portion of whose body is four or five times as 

 long as the thorax, and the thoracic lines probably white. A 

 second, Clavelina producta, has the thorax very short and 

 as broad as long, and the abdomen very long. Claveli7ia 

 pumilio, on the other hand, is nearly sessile and square. 

 We have gathered a species, probably identical with the 

 last, though much larger than the specimens described 

 by Milne-Edwards, at low water in the island of Herm. 

 Clavelina Rissoana is a JNIediterranean species, resembling 



