_c._ Several foramina are seen perforating the anterior part of the orbit. The most dorsal of these, perforating the lachrymal bone, is the =lachrymal foramen= (fig. 73, 13). Lying below and slightly external to this is a large foramen, through which part of the second branch of the trigeminal enters on its way to the infra-orbital foramen and so to the side of the face. Lastly, lying below these, and perforating the palatine, are two closely apposed foramina, the =internal orbital foramina=, through which part of the first or ophthalmic branch of the trigeminal nerve leaves the orbit, passing into the nasal cavity. _d._ The anterior part of the palate between the premaxillae and the maxillae is perforated by a pair of long closely apposed apertures, the =anterior palatine foramina= (fig. 75, 19). They transmit part of the trigeminal nerve. _e._ Towards the posterior part of the palate are two pairs of small =posterior palatine foramina= (fig. 75, 18). These perforate the palatine and transmit branches of the trigeminal nerve and certain blood-vessels. _f._ The =posterior narial opening= is bounded chiefly by the palatines. _g._ The =alisphenoid canal= (fig. 75, 21) is a short canal penetrating the base of the alisphenoid bone, and transmitting the external carotid artery. It lies between the foramen rotundum and the foramen ovale. _h._ Between the auditory bulla and the foramen ovale are seen two openings. The more external of these is the opening of the =Eustachian canal= (fig. 75, 22), which communicates with the tympanic cavity. The more internal is the =foramen lacerum medium= (fig. 75, 9), through which the internal carotid enters the cranial cavity. _i._ The =external auditory aperture= (fig. 75, 7) is a large opening with rough edges at the outer side of the tympanic bulla. _j._ Between it and the glenoid surface of the squamosal is the =postglenoid= foramen (fig. 75, 10) through which a vein passes out. _k._ Lastly, there is the great =foramen magnum= (fig. 75, 2), between the occipital condyles. Through it the brain and spinal cord communicate. C. THE RIBS AND STERNUM. [Illustration FIG. 76. STERNUM AND STERNAL RIBS OF A DOG (_Canis familiaris_) × 1/2. 1. presternum. 2. first sternebra of mesosternum. 3. last sternebra of mesosternum. 4. xiphisternum. The flattened cartilaginous plate terminating the xiphisternum is not shown. 5. first sternal rib.]