148 SIDNEY P. HAEMEB. 



My study of the metamorphosis of Pedicellina has led me 

 in the main to a complete confirmation of the account already 

 given by Barrois (No. 3), and summarized on pp. 312 and 313 

 of my previous paper on Loxosoma (No. 4), where I have 

 ventured on a criticism of Barrois' conclusions which I do not 

 find to be justified by my own investigation of the subject. 

 In opposition to my previous opinion^ I must now conclude 

 that the post-larval changes consist in a remarkable metamor- 

 phosis, and that the first bud is formed after the primary 

 individual has acquired its adult characters. Barrois has 

 published no figures illustrative of his statements, the actual 

 details of the process being difficult to understand from his 

 very short description, whilst the morphological nature of the 

 changes remains entirely obscure. The subject appears to me, 

 therefore, to deserve further consideration. 



The structure of the larva is well known from the researches 

 of Hatschek,^ and it will be unnecessary to describe it in more 

 than a few of its details. 



In the swimming attitude of the larva, the ciliated ring is 

 everted to the exterior, whilst from the oral face project two 

 prominent structures ; — the epistome, with its tuft of long cilia, 

 and the anal cone, on which opens the anus. During the re- 

 tracted condition, however, the ciliated ring is reflected to the 

 interior of the large vestibular cavity, whose outer walls are 

 formed by the fold of skin which bears the ciliated ring itself 

 (cf. PI. XVI, fig. 1). The floor of the vestibule is constituted 

 by the ventral or oral surface of the larva, being specially de- 

 pressed between the base of the epistome and the anal cone, 

 and at the sides of the latter. 



As Barrois has correctly stated, fixation takes place by the 

 oral surface, the larva being meanwhile in its "retracted" condi- 

 tion. PI. XVI, fig. 1, a median longitudinal section, will 

 serve to illustrate the method of fixation. It will be noticed 

 that the long axis of the stomach is approximately parallel 

 to the surface of attachment. 



1 Fide the summary of Hatschek's results in Balfour, ' Comp. Emb.,' vol 

 pp. 242—246. 



