THE STRUCTURE OF THE LARVA OF LANICE CONCHILEGA 107 



The " lippenorgan - of Owenia Jîliformis described first of ail by von 

 Drasche and afterwards by Watson (igoo), acts in a similar manner and 

 is said also to secrète a mucous substance or cément, in order to bind the 

 building materials together. From the analogy between the processes in 

 thèse two species of tube building Polychœta, Watson concluded that a 

 buccal gland existed in the lower lip of Terebella and Laiiice, which pro- 

 duced the cernent required in the formation of the tube, and he has 

 suggested that this gland is the bilobed organ which is occasionally seen 

 protruded from the mouth. 



After a careful examination of a séries of sections through the head of 

 Lanice conchilega, we hâve corne to the conclusion that this bilobed organ 

 is not a glandular, but a purely muscular organ. The sections were 

 lightly stained vvith Delafields hsematoxylin in the first instance, then 

 with acid fuchsin, and finally with méthylène blue. By this method 

 the faintest traces of mucin are readily shown. We found that an abun- 

 dant quantity of mucin is secreted in other parts of the mouth, and 

 externally in the prostomium,, but no trace of a sécrétion was visible in the 

 epithelium forming the external covering of the muscular buccal organ. 

 Just behind the buccal organ is a glandular crypt, the walls of which con- 

 tain a large number of mucous secreting cells, which probably produce a 

 part of the cément used in the building opérations. 



Dorsal gland. A more interesting feature in the structure of our larva, 

 is a large gland situated in the anterior région immediately behind the 

 supraœsophageal ganglion. This gland has been described in varions man- 

 ners. Claparede in his description of this larva noticed a group of large 

 cells in the région of the head, and took them to be brain cells. They are 

 very visible by transparence, and can also be seen in larvse younger than 

 those we hâve actually investigated. Cunningham and Ramage, in their 

 description, make no mention of thèse cells, nor do they figure in their 

 drawing of the larva. 



The species of annelid described by Giard(i878) under the name 

 Wartelia gonotheca, and which was discovered at Wimereux among the 

 branches of the hydrozoan Laomedea gelatinosa, is probably, as Fauvel 

 has recently pointed out, none other than the larva of Lanice conchilega. 

 GiARD himself admits a close resemblance to the larva described by Cla- 

 parede, but bases his belief, that the form in question is not the larva of 

 Lanice but an adult annelid belonging to a distinct group, mainly on the 



