46 Mam^nalia. Cete. 



the medullary canal of each remains distinct ; each moiety has its distinct distal 

 trochlea and phalanges ; and in each of them the second phalanx is modified to 

 be sheathed in a hoof : stunted portions of the other toes are'to be found in most 

 true Ruminantia suspended to the back part of the distal end of the so-called 

 * cannon ' bone, as ' spurious hoofs,' not reaching the ground. 



The Pelvic Arch and Appendages. The Iscliia are long, and with 

 the dorsal angles of the broad and thick tuberosities produced to- 

 wards the caudal vertebrce. The Femur never has a third trochan- 

 ter: the Medullary artery^ except in the Camelide, enters the/or<9 

 part of the shaft usually in its upper third : the inner border of the 

 rotular channel never developes an irregular prominence (as in Peris- 

 sodactyla) though here produced. In the Carpus the Ectocuneiform 

 is less, or not larger than the Cuboid : the Cuboid and Naviculare are 

 distinct bones in all except the restricted or horned Ruminants. 



Otnnivora. The Tibia and Fibula are generally distinct. In Dicotyles (Peccari) 

 the fifth as well as the first toe are wanting in the hind foot : the second toe is 

 small ; the third and fourth are very large, and form a symmetrical pair, show- 

 ing that the Artiodactyle structure essentially prevails, although the toes, by the 

 non-development of the fifth, are, exceptionally, reduced to three in number. 



Ruminantia. The Oa innominaiiim is elongate, with the iliac portion concave 

 lengthwise, convex across, externally, with the expanded anterior end divided 

 by a ridge into two portions articulating with sacrum. The Ischium extends 

 back from the acetabulum with the tuberosity bending upwards. The Pubes are 

 slender. The Hind Limbs always exceed the fore limbs in length. The shaft 

 of the Fibula exists as a sclerous tissue in all Ruminantia. The Naviculare or 

 Scaphoid is almost always confluent with the Cuboid. The Metatarsal segment is 

 generally represented by the third and fourth metatarsals confluent : the distal 

 ends of the second and fifth being ossified and supporting the small digits termin- 

 ated by the ' spurious hoofs.' [In the Camelidce the scapula is broader than in 

 homed Ruminantia, and has its spine produced : the scaphoid is not confluent 

 with the cuboid : the canal for the medullary artery enters the back part of the 

 shaft of the femur; the borders of the rotular channel are subequal.] 



XL CETE. 



The Skull is large, the size being due in most Cete to the develop- 

 ment of the jaws, which in some Whales [e.g. Bala^nidae, and Physeter 

 macrocephalus) is excessive. The Skull of the Balaenidas is more 

 symmetrical than that of the toothed Cete. T\iq Mastoids are always 

 distinct from the Petrosals. The Tympanic generally presents a 

 peculiar conchoidal shape, and is extremely dense in texture. 

 Laclirym,al bones are generally absent. The C rihr if orm plate is also 

 usually rudimentary, or absent (Physeter). The JVasal bones are 

 hort, rudimentary, or absent (Physeter). The Frontal bones fre- 



