M. R. Leuckart on the Young States of some Annelide's: fSof 



which are subsequently converted into the middle hodifP^JMB^ 

 which, as is well known, present by far the largest appendage^! ' 



The mature Chatopterus lives in a free tube formed by itself. 

 In this respect it is not without interest that we learn from 

 Busch, that the larvse observed not unfrequently exuded a 

 slimy mass in the last days of their existence, with which they 

 attached themselves to the side of the vessel in which they 

 were kept. 



I regret that during my residence in the Mediterranean I had 

 nb opportunity of becoming acquainted, by my own obser- 

 vations, with these int(!resting larvse, which appear to possess 

 rather a wide distribution. In this case it is probable that many 

 other points of resemblance with the structure of Chcetopterus 

 would have been discovered. But in Nice the larvse of Anne- 

 lides are generally rarities, at least it was so while I was there. 

 Except the spinose forms above described, only a few were dis- 

 covered, and these mostly at a time when my attention was taken 

 up with other investigations. Amongst these few there is how- 

 ever one upon which I may add a few words, although, properly 

 speaking, the name of larva is no longer applicable to it, as it* 

 scarcely exhibits any traces of its provisional organs. It is ^• 

 young Alciope (A. Raynaudii), which I took up one day in the 

 Bay of Villa Franca with a number of Firoloides, amongst which 

 it was swimming about*. 



The beautiful, transparent little animal (PI. VII. fig. 6) mea- 

 sured 4J lines, and its body consisted of three distinctly sepa- 

 rated regions, — the head with the neck, the true body, and a 

 tail, — although the mature animal, as is well known, exhibits no 

 trace of any such division f. The middle region was by far the 

 largest of these divisions ; it measured about three lines in length 

 and nearly a fourth of this in breadth ; it was broadest in the 

 middle and gradually diminished a little towards the extremities, 

 especially in front. In this middle region eight segments were 

 distinctly to be recognized ; they resembled those of the mature 

 animal in every respect, so that I need not describe them parti- 

 cularly. But I may observe, that the bristles of the first pair of 

 pedal tubercles were very much shorter and less numerous than 

 those of the others, and especially the hinder ones_, which were 

 the most developed in every respect. The neck was considerably 

 narrower than the foremost segment to which it was attached, 

 and probably measured scarcely a third of the greatest breadth 

 of the middle region. It was as long as broad, and exhibited 

 three segments, or rather three pairs of segmental appendages, 



* I also met with Alciope Candida several times in the Bay of iViUa 

 Franca. ''f'^^^ 



t See Krohn, Wiegmann's Archiv, 1845, p. 171. '-'^ 



18* 



