FELTS SPEL^A. 53 



formed by the basi-occipital and the basi- and pre-sphenoids, in opposition to the 

 more strict vertebral theory of Professor Owen,^ who considers the vomer as the centrum 

 of the nasal vertebra. The posterior edge of the plate expands laterally into a transverse, 

 nearly vertical plate, concave posteriorly, which closes the anterior end of the cranial 

 cavity ; from its being full of small foramina this is called the cribriform plate. From the 

 lower and outer edges of these two plates spring others remarkable for their thinness and 

 delicacy, which form a highly complicated tissue-like mass of bone, filling the greater part 

 of the facial cavity, and sending prolongations upwards and backwards into the frontal 

 sinuses, backwards and downwards into the anterior sinuses of the pre-sphenoid, and for- 

 wards into the nostrils. This mass is attached to the maxillaries, the frontals, vomer, and 

 presphenoid, by delicate and thin articulations ; and the whole is so arranged that the air 

 breathed through the nostrils must pass over the greater part of its surface. Through the 

 foramina in the cribriform plate pass the branches of the olfactory nerves, which are spread 

 over the large surface afforded by the convolutions of the bone. The whole mass thus 

 described is called a sense-capsule by Professor Owen.^ This bone is naturally highly com- 

 plicated in animals endowed with a fine sense of smell, such as the Felidse. In the 

 common cat it looks like a mass of lightly squeezed silver-paper. In the larger Feles it is 

 of course somewhat thicker and coarser, and more slightly packed, but it is still of great 

 delicacy and beauty. The pattern of the foramina in the cribriform plate may, perhaps, 

 vary in the different species, but the position of the bone in the skull renders a comparison 

 difficult and uncertain. In the smaller skull of Felis spelma the plate appears like a 

 beautiful plate of Saracenic tracery filling the end of the cranial cavity when viewed 

 through the foramen magnum. 



§ 15. Wormian (Pis. VI, VII, IX). — The Wormian or inter- parietal is a small 

 triangular bone occupying the apex of the occipital crest, and firmly wedged in between 

 the parietal and supra-occipital, the sutures being of considerable depth. The develop- 

 ment of its downward processes is very variable, but sometimes they extend down to the 

 squamosal, and even the mastoid, thus separating the supra-occipitals from the parietals. 

 Its inferior surface forms the highest part of the cranial cavity. 



Muscles. — The Wormian bone gives origin to several small muscles that regulate the 

 movement of the ear ; for their names we refer to the second volume of Straus-Durckheim's 

 great work on the cat, which we have so often quoted. 



§ IG. Parietals {?h. VI, VII, IX, No. 7).— The parietals form the roof of the greater 

 part of the cerebral cavity, and appear ou the exterior of the skull as two nearly rectan- 



1 'Homol. Vert. Skel.,' pis. 1 and 3. 



2 Ibid., pis. 2 and 3. 



