TUNIC ATES. 61 



The chain Salpa, before the ripening of its spermatozoa, is to be regarded as a nurse. 

 To the writer it seems that these differences, apparently so marked, are in reality 

 reconcilable; 'and that it is ])artly a question of definition, and partly due to the fact 

 that the tissues of the individuals of the chain are outgrowths from the solitary form, 

 so that it is difficult to say which should be regarded as the ])arent of either sexual 

 element. 



The individuals of the chain Salpce are variously arranged, being placed with their 

 axis parallel or transverse to the chain, or in some intermediate position. The 

 members of the chain are held together by means of spurs extending from one to 

 another. 



On our east coast a single species, /Sa^ce spinosa, (often called /S. cdboti), occurs, 

 forming chains a foot in length or even more, each chain containing two rows. 

 The body is perfectly transparent, but is frequently tinged with I'ed or blue. At 

 times they are very abundant, filling the water for miles. 



In the tropical seas they are more abundant, and a considerable number of species 

 have been described. 



At present, as we have seen, the ascidians are placed at the bottom of the verte- 

 brate series, but among the so-called worms exists a form, Halanoglossus, which may 

 belong here, occupying a place below the tunicates. This view receives considerable 

 confirmation from the researches of Mr. Bateson on the species which lives in the 

 North Carolina waters. Unlike the previously known forms, this species does not pro- 

 duce a Tornaria larva, but develops directly into the adult by processes which recall 

 those of Amphioxus, next to be taken up. Halanoglossus and its peculiar larva are 

 figured and described in our first volume. 



J. S. KiNGSLEY. 



