20 



decrease almost to a point, and incline towards the upper lobe of the tail, indicating the hetero- 

 cercal structure : the neural spines of several of the anterior vertebrae coalesce, and form a 

 continuous ridge : superorbital as well as suborbital scale-bones are present in the skull. 



Hunterian. 



49. The skeleton of a larger Pike (Esox Lucius). The number of the vertebrae is 



the same in this as in the preceding skeleton. 



Notwithstanding the superior age of this specimen, most of the neural arches remain 

 unanchylosed to the centrums : the sutures of many of the parapophyses may also be seen : 

 both epipleural and epineural accessory spines are here present. 



Mm. South. 



50. The skull of a Pike (Esox Lucius], with the integuments, and the branchiae 



injected. Hunterian. 



51. A similar specimen. Hunterian. 



52. A longitudinal vertical section of a skull of a Pike (Esox Lucius), showing the 



cranial and subcranial canals. 



The long posterior process of the epitympanic for the articulation of the large subopercular 

 bone may here be noticed : the four branchial arches of the left side are preserved. Laniari- 

 form and villiform teeth are supported by the vomer, as well as by the palatine, premaxillary, 

 and premandibular bones. The edentulous maxillary forms a larger proportion of the upper 

 border of the mouth than in most osseous fishes, and the affinity to the Salmonidce is hereby 

 indicated. 



Presented by Prof. Owen. 



53. The palatal and premandibular bones of a large Pike (Esox Lucius). The 



palatines show a coarse variety of the rasp-like teeth. In the lower jaw some 

 new-formed teeth may be observed, the ligamentous bases of which have not 

 been affixed by ossification to the substance of the jaw. Hunterian. 



54. The palatine and one of the pterygoid bones of a large Pike (Esox Lucius). 



Purchased. 



55. The lower jaw of a large Pike (Esox Lucius'), which weighed 16 Ibs. 



Presented by William Thompson, Esq., 1820. 



