152 REPORT — 1859. 



bones form the walls of the posterior nares. The pterygoid processes extend out- 

 wards and backwards, are twisted over and nearly cover the two posterior alveoli. 



The lower jaw is a dense massive bone, the sides forming a right angle with 

 the broad flat vertical rami. The length of the sides from the incisive edge to 

 the angle of the jaw is fully 8 inches, and the depth about 2i inches. The 

 perpendicular height of the rami from the angle of the jaw to the condyle is 6^ 

 inches ; and from the condyle to the anterior point of the coronoid process, the 

 distance is 4 inches, the upper border of the coronoid being nearly on a level 

 with the condyle. The symphysis at the fore and under part of the two rami is 3g 

 inches in length, with a large grooved foramen menti and another foramen 

 behind, which communicates with the maxillary canal. The upper anterior inci- 

 sive portion is 1\ inches, having a rough, pitted, irregular surface. A special 

 peculiarity marking the lower jaw is the acute inflected angle, the distance 

 between the two inner points of the angles being only 3 T \ inches. The alveolar 

 process of the lower jaw is seven inches in length, slightly curved outwards and 

 downwards anteriorly. There is another curve outwards and upwards at the 

 posterior termination, where it protrudes by an inflated extremity through the inner 

 part of the root of the coronoid process, directly above the posterior maxillary 

 foramen. 



Eleven molar teeth, with two large transverse bi-tuberculated ridges, and a smaller 

 ridge behind, are implanted by two roots in sockets about an inch deep, on each 

 side of the lower jaw. The roots of the teeth are flattened transversely, corre- 

 sponding to the transverse coronal ridges. The anterior root is curved backwards, 

 longer and more fully developed than the posterior one, and penetrates the inner 

 alveolar wall in several places. The roots of the molars in front are solid and 

 bifurcated at the apex ; whilst those behind have the roots of nearly equal length, 

 and are hollow at the apex. The molar teeth in the upper jaw have two transverse 

 tri-tuberculated ridges, with a ridge-like thickening of the cervix anteriorly and 

 posteriorly. Each tooth has three slightly diverging roots, the inner root compressed 

 longitudinally, the two outer roots compressed transversely; and the external anterior 

 root is also curved backwards like the corresponding one of the lower jaw. Only 

 the eight anterior molar teeth have been in use for mastication, the three posterior 

 being nidamental ; and the points of the foremost two or three molars are much 

 worn down, showing a thin dark outer layer of cement, succeeded by a thicker 

 coat of enamel, which surrounds a light-brown dentine. 



This skull agrees with the brief descriptions which I have seen of the " Manatus 

 Senegalensis ;" and the locality whence it was derived confirms this view. Skulls 

 of this species, however, appear to be rare in our public museums ; for there are 

 none described in the Catalogue of the Royal College of Surgeons of London, and 

 none in that of the British Museum, as existing in either of these valuable osteological 

 collections. 



In the British Museum Catalogue for 1850, the number of grinders in the 

 genus Manatus is said to vary according to the age or state of the specimens, but 



when complete they are m '. It is stated that the front ones are often deci- 

 duous ; hence Sir E. Home describes them as m — -, and Cuvier as m . In 



o — 6 8 — 8 



this skull, the teeth are well preserved, — 39 remaining in their sockets, and 5 

 distinct empty sockets for others. The dental formula is therefore m — =44. 



Notice of the Duration of Life in the Actinia Mesembryanthemum when 

 kept in confinement. By Dr. M'Bain. 



Notice of the Skull of a Wombat from the Bone-Caves of Australia. 



By Dr. M'Bain. 



