300 THE SKELETON OF THE RABBIT. 



2. The sense-capsules. Each of the organs of special sense 

 has in the embryo rabbit, as in the dog-fish, a protect- 

 ing investment of cartilage or strong connective tissue. 

 In the ease of the olfactory and auditory organs these 

 capsules are closely connected with the cranium, and 

 in the adult are more or less extensively ossified. 

 Membrane-bones are also developed in immediate 

 relation with the sense-capsules, and may conveniently 

 be considered with them. 



a. Bones in relation with the olfactory capsules. The 



olfactory capsules are very large in the rabbit, 

 and occupy a great part of the facial portion 

 of the skull. They are so closely connected 

 with the ethmoidal region and with the upper 

 jaw, that certain of the bones may be referred, 

 with equal propriety, to either of these divisions. 



i. The nasals are a pair of elongated membrane- 

 bones, forming the roof of the nasal cavities. 

 They unite suturally with the frontals behind, 

 and with each other in the median plane. 



ii. The ethmo-turbinals are intricately folded laminsB 

 of bone, fused to the lower surface of the cri- 

 briform plate of the ethmoid, and occupying 

 the upper and posterior part of each nasal 



cavity. 



iii. The maxillo-turbinals are a pair of somewhat 

 similar, but more delicate and more complex 

 bones, lying in the anterior portion of the 

 nasal cavities, in front of the ethmo-turbinals. 



iv. The naso-turbinals are a pair of thin laminae of 

 bone, folded to form pouches, and fused with 

 the under surfaces of the nasal bones. 



V. The vomers are a pair of slender blade-like bones, 

 fused with each other along their ventral 

 margins, and embracing the lower edge of 

 the mes-ethmoid cartilage. Behind they are 



