408 PEOr. C. STEWAET ON THE 



A large aperture (ductus utriculi) in the floor of the utricle 

 opens into the recessus, and from the postero-superior parts of 

 the recessus a tube-like passage (canalis recessu saccularis) leads 

 into the saccule. 



As the skin was required for other purposes, the nature of the 

 superficial portion of the ductus endolymphaticus and its opening- 

 could not be determined, 



LiEMAEGUS BOEEALis. Faiu. SpiuacidsB. 



In this species the labyrinth has a considerable resemblance 

 to that of Notidanus. 



The ductus endolymphaticus, after passing through the carti- 

 laeinous roof of the skull, takes the usual forward course, but 

 more directly upwards than in most cases ; at the extremity of 

 this portion it ascends nearly vertically to its cutaneous opening. 

 The recessu-sacculine and posterior utriculo-sacculine canals are 

 much wider than iu Notidanus. The sacculus is small, with the 

 lagena cochlise as a large depression of its postero-inferior angle. 

 The dorsal extremities of both portions of the utricle are more 

 dilated than in Notidanus. 



Lamna coentjbica. Fam. Laranidse. 



On examining this form, one is at once struck by the apparent 

 fusion of portions of the two divisions of the utricle, forming a 

 structure that has a close superficial resemblance to the sinus 

 supei'ioris utriculi of the Teleosts ; their cavities, however, 

 remain distinct. 



In front and parallel to this may be seen the ductus endo- 

 lymphaticus passing upwards to penetrate the skull ; it then 

 passes forwards in close contact with the skull for about 18 mm., 

 and bends for a short distance backwards before ascending 

 nearly vertically to its external opening. The sacculus is small 

 and cylindrical, terminating in a lagena cochlia? wider than 

 itself. The recessus utriculi opens into the utricle above and 

 the sacculus behind by a common orifice. At the same point 

 the ductus endolymphaticus arises. Two small ramuli neglecti 

 pass to the macula neglecta on the outer side of the posterior 

 utriculo-sacculine canal. 



Alopecias vtjlpes. Fam. Lamnidse. 

 In this Shark the ductus endolymphaticus lies in a similar 

 position to that in Lamna, well anterior to the blended portions 



