On the Young Stages of a few Annelids. 311 



Annelid belonged ; while it is this very absence of teet and 

 bristles, as well as the distinct separation of the digestive 

 cavity into oesophagus, stomach, and intestine, plainly described 

 by him in his young worm, which should have guided him, as 

 well as subsequent writers on this subject, in referring the larva 

 to its proper place. Had it not been for the deceptive appear- 

 ance caused by the temporary presence of antennae and their 

 resemblance to Polynoe larvae, this would undoubtedly have 

 been done long ago, especially when taking into consideration 

 the differentiation of the digestive cavity, so prominent in 

 Loven's larvae ; this separation takes place in other Annelid 

 larvae, long after the family and sometimes even the generic 

 characters have been fully developed. The early growth of 

 bristles and the resemblance of the young larvae of Polynoe to 

 the adult, at so young a stage, should at once have directed 

 attention to such an anomalous type as that of Loven's, having 

 no feet or bristles long after the young worm had lost its em- 

 bryonic character, as well as all trace of the row of vibratile 

 cilia round the head. 



The passage of Loven's figures from the condition with a 

 disk to the most advanced stage he observed is somewhat 

 abrupt. I have been able to supply this defect in the obser- 

 vations given below. See Figs. 7-16. Although my larvae 

 differ somewhat from those of Loven, there can be no question 

 of the family identity of the two. In the youngest larva, Fig. 

 3, we find, as observed by Lovdn, no trace as yet of any articu- 

 lations ; but we have besides the large circle of vibratile cilia 

 round the anterior extremity (v) described by Loven, a similar 

 powerful ring (V) round the posterior extremity. This anal 

 circle either does not exist in Loven's larva or must have es- 

 caped his attention. Our larva is like Loven's, transparent as 

 glass ; it has in addition, following the course of the two vibra- 

 tile rings, a single row of most brilliantly colored orange pig- 

 ment spots of different shades and sizes ; similar pigment spots 

 are scattered in three unequal rows along the unarticulate 



