540 Proceedings of the Royal Irish Academy. 



The scaphoid : — Defective at that part nonnally articulating with. 

 the trapezoid. 



The semilunar : — Prolonged reiy much to ulnar side, where it ar- 

 ticulated with the entire of the inter-articular fibro-cartilage — a reiy 

 large facet for the uncifoiTa. 



The cuneiform : — Indistinguishable as a separate bone. 



The pisiform : — Also indistinguishable. 



The trapezium had an additional facet at the site of the external 

 angle, for articulation with the first metacarpal bone. The groove on 

 the anterior surface indistinct. Another facet for the "anterior tra- 

 pezoid." 



The trapezoid posterior : — Yeiy large, extending upwards to the 

 level of the head of the os magnum, wliich it resembled. A constriction 

 was indicated at the level of the ordinary bone, and the additional 

 portion seemed to be borrowed from the scaphoid, which was deficient 

 to a corresponding extent. The bone did not reach the anterior surface 

 of the carpus. 



The anterior trapezoid(?) : — About the size of a large pea ; wedge- 

 shaped, with the base anteriorly occupying the position of the anterior 

 surface of the trapezoid proper. It articulated above with the poste- 

 rior trapezoid and the scaphoid, below with the third metacarpal bone 

 (that of the index finger), and latterly with the trapezium and the os 

 magnum. 



The os magnum : — The head was not rounded on the outer side ; 

 -an additional facet for the anterior trapezoid. 



The uncifonn : — Large, no process ; a very large facet for the semi- 

 lunar bone, and another on its anterior and upper sui-face for the os 

 triquetrum. 



The "os triquetrum" : — Situated anteriorly to the unciform and the 

 ulnar extremity of the semi-lunar bone, internal to which one of the 

 angles projected backwards, and presented its apex on the posterior 

 surface of the carpus. It presented two surfaces, thi-ee margins, and 

 three angles. The surfaces were both rough, and had trii-adiate de- 

 pressions, indicating the fusion of the bones ; the inner or ulnar sui-f ace. 

 gave attachment to the hypothenar muscles, the outer or radial entered 

 into the formation of the anterior caipal concavity. The anterior margin 

 gave attachment to the annular ligament; the superior edge had attached 

 to it a very strong radio-triquetral ligament. The posterior margin 

 was divided into two parts : the inferior narrow, and attached by a 

 ligament to the anterior siuiace of the unciform, corresponding to the 

 position of the process ; the superior portion broader, with an articular 

 facet for the unciform bone. The anterior angle was tubercular, and 

 gave attachment to the tendon of the flexor caipi ulnaris. The pos- 

 terior angle had a smooth facet for articulation with the apex of the 

 ulnar styloid process, and it also gave attachment to the internal lateral 

 ligament. The inferior angle had attached to it ligaments extending 

 to the bases of the last two metacarpal bones. 



