Special Osteology. Insectivora. 3 



A 



groove beneath i\ie pubic botmdary of the obturator foramen (of. i.). The linca 

 aspcra of the fanur is little developed, and the outer articular condyle is nar- 

 rower than the inner one, the reverse being the case in Man. The articulation 

 of the bones of the leg with the tarsal bones favours the oblique position of the 

 foot, and adapts it for grasping. The ectoeiineiform has commonly a convex 

 articular surface for the hallux, which articular surface in Man is nearly flat : 

 the diiference being significant of the diiferent function of the hallux in the 

 two species : the chief fulcrum of the foot requiring a firm articulation in Man 

 but in the higher Apes, e.g. Gorilla, requiring great extent of motion for the 

 function of this opposable grasping thumb. 



Lemuridce. In the Spectres (Tarsius) the excessive length of the calcaneum 

 is remarkable : hence their generic name. 



III. INSECTIVORA. 



The Shull. The cranial cavity is small, and the outer surface is 

 commonly smooth, and devoid of crests. The Orlital and Temporal 

 foss(B communicate freely (? Galeopithecus^). The Malar bones are 

 generally slender, and are usually either suspended in the zygoma 

 {e.g. Galeopithecus), or applied like a splint along the outer and 

 under side of the junction of the zygomatic with the maxillary 

 [e.g. Urinaceus, Gymnura). In Centetefi the Malar is entirely absentf 

 and the Zygomatic arch incomplete. The Tympanic is frequently 

 present as a delicate ring. In Talpa the pyriform skull is prolonged 

 by a prcenasal ossicle. 



The Vertelral Column. All the processes are relatively small 

 throughout the vertebral column. The Sacrum, is narrow. The 

 Syraphysis Pubis is short or absent {Talpa, Bar ex). 



In Tal'pa the first sternal bone, or Manubrium, is of unusual length, being 

 much produced forward, and has its under surface produced downwards, in the 

 shape of a deep keel, for extending the origin of the pectoral muscles. 



Bones of the Limls, All the Insectivora have perfect Clavicles ; 

 the Scapula is generally long ; the Legs short and unguiculate ; the 

 Feet plantigrade, generally five-toed, none opposable. 



The peculiar development of certain of the Limb-bones obtaining in Talpa 

 deserve special notice ; thus The Clavicle is cubical (an unique form in Vertc- 

 brata), is articulated firmly to the anteriorly projecting breast-bone, but attached 

 to the acromion by ligament. The Scapula assumes Ornithic proportions, its 

 length being more than six times its extreme breadth, it is trihedral save in the 

 middle, where it is cylindrical. The Humerus, as in most fossorial animals, is of 

 great breadth, and provided with singular inequalities of surface for the attach- 

 ment of muscles; it is a sub-quadrate, lamelliform bone, wdth a proximal 

 articulation for the clavicle as well as for the scapula. f The Carpal series has 

 added to it a large supplementary sickle-shaped bone, extending from the radius 

 to the metacarpal of the pollex. 



* The orbit is partly defined behind by long and slender processes of the frontal, 

 t And, as in 7nost animals that scratch, has the inner condyle perforated. 



