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PHYLUM CItORDATA 



443 



of the distal row are, reckoned in the same order, trapezium (trpm.), 

 trapezoid (trpz.), magnum (mag.), and unciform (unc.). 1 



The five metacarpals are all small but relatively narrow and 

 elongated bones, the first being smaller than the rest. Each of 

 the five digits has three phalanges, except the first, which has 

 only two. The distal (ungual) phalanges are grooved dorsally 

 for the attachment of the horny claw. 



The pelvic arch (Fig. 1096) contains the same elements as in the 

 Pigeon, but the union of the ilium with the sacrum is less intimate, 

 the acetabulum is not perforated, and the pubes and ischia of oppo- 

 site sides unite ventrally in a symphysis (sy.). The three bones 

 of the pelvis ilium, pubis, and ischium are separate ossifications 



rad 



FIG. 1095. Lepus cuniculus. Distal 

 end of fore-arm and carpus, dorsal 

 view, the bones bent towards the 

 dorsal side so as to be partly sepa- 

 rated, cent, centrale ; cun. cuneiform ; 

 lun. lunar ; mag. magnum ; rod. 

 radius ; sc. scaphoid ; trpz. trapezoid ; 

 trpm. trapezium ; uln. ulna ; unc. 

 unciform ; / F, bases of metacarpals. 

 (After Krause.) 



FIG. 1096. Lepus cuniculus. Innomi- 

 nate bones and sacrum, ventral aspect. 

 acet. acetabulum ; U. ilium ; isch. ischium ; 

 obt. obturator foramen ; pub. pubis ; 

 sacr. sacrum ; sy. symphysis. 



in the young Rabbit ; but in an adult animal complete fusion 

 takes place between the bones. The ilium and ischium meet in 

 the acetabulum or articular cavity, which they contribute to form, 

 for the head of the femur ; but the remainder of the cavity is 

 bounded, not by the pubis, but by a small intercalated ossification 

 the cotyloid bone. The ilium (il.) has a rough surface for articu- 

 lation with the sacrum. Between the pubis (pub.) in front and 

 the ischium (isch.) behind is a large aperture the obturator foramen 

 (obt.). The femur is rotated forwards when compared with that 



1 The homologies of these bones are not quite certain, but are very probably 

 as follows * scaphoid = radiale, lunar == 1st centrale, cuneiform = inter- 

 medium, pisiform = ulnare, centrale = 2nd centrale, trapezium = 1st distale, 

 trapezoid = 2nd distale, magnum = 3rd distale, unciform = 4th and 6th 

 distalia. 



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