458 ZOOLOGY sect. 



arranged in two rows, one of the bones — the navicular (nav.) — 

 being intercalated between the two rows. In the proximal row are 

 two bones — the astragalus (ast.) and the calcaneuni (cal.) — both 

 articulating with the tibia ; the calcaneum presents behind a long 

 calcaneal 2>^'occ$s. The distal row contains three bones, the mcso- 

 cuneiform,. ecto-cuneiform and cuboid (cuh.) ; the ento-cimciform, 

 which commonly forms the most internal member of this row 

 in other Mammals, is not present as a separate bone.^ 



There are four metatarsals, the hallux or first digit being vestigial 

 and fused with the second metarsal in the adult. The proximal 

 end of the second is produced into a process which articulates 

 with the navicular. Each of the digits has three phalanges, which 

 are similar in character to those of the manus. 



The coelome of the Rabbit differs from that of the Pig^eoD and 

 Lizard in being divided into two parts by a transverse muscular 

 partition, the dicq^liragm. The anterior part, or thorax, contains 

 the heart and the roots of the great vessels, the lungs and bronchi, 

 and the posterior part of the oesophagus. The posterior part, or 

 ahdomen, contains the stomach and intestine, the liver and pancreas, 

 the spleen, the kidneys, ureters and urinary bladder, and the organs 

 of reproduction. 



Digestive Organs. — The teeth (Fig. 1082) are lodged in sockets 

 or alveoli in the premaxillae, the maxilise, and the mandible. In 

 the premaxillse are situated four teeth — the four upper incisors. 

 Of these the two anterior are very long, curved, chisel-shaped 

 teeth, which are devoid of roots, growing throughout life from per- 

 sistent pulps. Enamel is present as a thick layer on the anterior 

 convex surface only, which accounts for the bevelled-off character 

 of the distal end — the layer of enamel being much harder than the 

 rest, which therefore wears more quickly away at the cutting 

 extremity of the tooth. Along the anterior surface is a longitudinal 

 groove. The second pair of incisors of the upper jaw are small 

 teeth which are lodged just behind the larger pair. In the lower 

 jaw are two incisors, which correspond in shape with the anterior 

 pair of the upper jaw, the main difference consisting in the absence 

 of the longitudinal groove. The remaining teeth of the upper jaw 

 are lodged in the maxilhie. Canines, present in most Mammals as a 

 single tooth on each side, above and below, are here entirely 

 absent, and there is a considerable space, or diastema, as it is. 

 termed, between the incisors and the teeth next in order — the 

 pre-molars. Of these ^here are three in the upper jaw and two in 

 the lower. They are long, curved teeth with persistent pulps like 

 the incisors, the first smaller than the others and of simple shape, 



^ In all probability the homologies of these bones are as follows : — astragalus 

 = tibiale + interniodiuin, calcaneiun ^ fibulare, navicular = centrale, cnto-cunei- 

 form=lst (li.stale, moso-cuneiform = 2nd distale, ecto-cuneiform = 3rcl distale, 

 cuboid = 4th and 5th distalia. 



