N 



410. A section of the jaw of a Carckaria*, in which part of the membranous rover- 

 ing of the recumbent teeth is preserved in a dry state. 



Presented by Prof. Owen, F.H.S. 



417. The maxillary and mandibulor arches of the Long-finned Shark 



macropler**). The pointed summits of the teeth of the lower jaw arc longer, 

 narrower, and continued wore abruptly from the base, than those of the 

 upper jaw. JIunterian. 



Family Lamnid<r. 



418. The cranium with the maxillary and mandibular arches, ami the body of tin 

 atlas, of the Porbeagle Shark (Lamna cornubicd). 



It show* well the tripodal rostrum and the form and succession of the teeth. The max- 

 illary arch is suspended by it* palatal basis ; the apex being attached to the vomerine extre- 

 mity of the basicrauial cartilage. A portion of the right tympanic pedicle is preserved. 



With this skull is placed the fossil tooth of a gigantic extinct Shark, having the sanir 

 characteristic processes at the base of the crown, to which it* generic name, Ototlut, has 

 reference. 



. Brit. 



41U. A cranium of the Porl>eaglc Shark (Lamna cornubica). 



It shows the fractured occipital surface which was anchylosed with the body of the atlas, 

 the wide anterior vacuity in the cartilaginous parietes of the cranium, the pterygoid archen 

 connate at both endt with the basis cranii as in the embryos of Osseous Fishe*, and the three 

 peculiar rostral processes which converge and coalesce at their anterior extremities to form 

 the framework of a kind of cut-water, which prolongs the skull in advance of the jaws. A 

 great proportion of the semioasified cartilage is covered by the pavement of fine ganoid 

 tubercles forming the substance called " shagreen." 



Presented by Dr. Leach, F.L.S. 



420. A series of vertebral bodies of the Porbeagle Shark (Lamna ronmbica). 



Presented by Dr. Leach, F.L.S. 



A series of vertebral bodies of the Lamna commbica. 



One extremity shows the terminal cone ossified to the centre ; at the other end a vertical 

 section of the centrum shows the longitudinal osseous plates which unite together the ter- 

 minal cone*. 



Pretexted by Dr. Leach, F.L.S. 



