BY WILLIAM A. HASWELL, M.A., B.SC. 93 



processes which articulate with the first vertebra are prominent, 

 the first vertebra being wedged very closely into the median recess 

 between them and very closely united to the skull, except in the 

 middle line above, where a considerable interval occupied by 

 fibrous tissue intervenes between the hinder part of the skull and 

 the neural arch.* The apertures for the vagi, which are very large, 

 are placed immediately above and in front of these lateral 

 processes, and above and a little external to them are a pair of 

 smaller apertures of unknown function. There is no trace of 

 a median occipital crest. In the auditory region the elevations 

 corresponding to the anterior and posterior semi-circular canals are 

 prominent, though rounded, and less sharply marked off than in 

 some nearly-related forms ; between the anterior elevation and 

 the lateral border of the skull is a rather deep hollow. The postero- 

 lateral angles of the skull are somewhat curiously modified, the 

 arrangement being more like that observed in Carcharodon than 

 in Scyllium. The angles are drawn out into prominent processes, 

 each of which exhibits three divisions, an antero-superior, an 

 anteroinferior, and a posterior. The antero-superior is continued 

 into the very prominent vertical ridge which separates off the 

 upper surfaces of the cranium from the lateral. The antero- 

 inferior forms the hinder portion of a ridge which bounds 

 superiorly the articular surface for the hyo-mandibular. The 

 posterior, which extends outwards and backwards, is grooved above 

 for the glossopharyngeal, the aperture of exit of which is situated 

 at its base ; below it developes a ridge with which some of the 

 ligaments for suspending the lower jaw appear to have been 

 connected ; this ridge occurs also in Cheiloscylliv.m ; it runs 

 forwards and inwards and ends some distance behind the basal 

 angle. The articular surface for the hyo-mandibular differs from 

 that of all forms with which I am acquainted f in being a very deep, 

 almost conical hollow, which is situated below and a little in front 

 of the anteroinferior process already mentioned. It is in the 



* A similar arrangement occurs in Cheiloxcyllium. 



t The corresponding articular surface in Cheiloscyllium is a wide and shallow concavity 

 without any definite upper border, but with the lower border rather prominent, and formtd 

 by the ridge mentioned above as giving attachment to ligaments. 



