12 HOVLE, PterygioteiitJiis margaritifera. 



arborescent fibres just described, though not so deeply as 

 the scales. It appears from a series of frontal sections 

 that this tissue bends round and partly encircles the 

 anterior part of the organ. 



Over all this is a fairly thick fibrous layer, but I have 

 not found any traces of an epithelium covering this. 



III. The Branchial Organs are also paired and 

 situated just at the root of each gill {^Fig. i, br}). In the 

 female specimen examined they are almost covered, when 

 looked at from the ventral aspect, by the swollen nidamen- 

 tal glands. They measure about 075 mm. in the largest 

 diameter ; neither in these nor in the siphonal organs did 

 I see under a lens any trace of the lustre observed in 

 some of the ocular group. As regards the minute 

 structure, Fig. 6 shows a median longitudinal section of the 

 left hand one. 



006 



Fio. 6. 

 Sagittal section of one of the branchial organs; cut., 

 central mass; /.w., fibrous n-ass; «.«., nerves; p.c, posterior 

 cup. 



