174 ODOXTORNITHES. 



The Fibula. (Plate XXXIII.) 

 The fibula of Apatornis appears to have been as much reduced in size 

 as in most existing birds. In one specimen (number 1734) it is a 

 slender rod, moderately thickened above, and tapering- to a point at the 

 distal end, where its attachment to the tibia appears to have been as slight 

 as in any living bird. 



The following are the main dimensions of the fibula in this specimen 

 of Apatornis : 



Measurements of Fibula. (Apatornis celer, No. 1734.) 



Length of fibula, 28. mra 



Transverse diameter of proximal end, 2.5 



Antero-posterior diameter of proximal end - 1. 



Greatest transverse diameter of shaft, 2.5 



The Tarso-metataesus. (Plate XXXIII.) 

 The tarso-metatarsal bone of Iclithyomis appears to be composed of 

 the same number of elements, united in the same degree, as in living birds, 

 a condition similar to that prevailing- in the wing. The resulting tarso- 

 metatarsal bone may be compared with the same bone in the Tern, which 

 it considerably resembles, although rather more robust in proportion to 

 its length. On the proximal end, the articular faces are slightly less 

 excavated than in that genus. The posterior part of the upper end is 

 imperfectly preserved, but a " calcaneal process " was present, though 

 probably not as well developed as in Sterna. The anterior face of the 

 shaft is excavated proximally, and perforated by a small foramen between 

 the upper ends of the third and fourth united metatarsals. On the posterior 

 surface of the bone, a shallow groove runs down from the foramen along 

 the shaft, indicating the line of suture between these metatarsals, and a 

 similar parallel groove behind shows the line of union of the second and 

 third metatarsals. 



On the anterior aspect of the middle metatarsal, and just below its 

 proximal end, is a prominent tubercle, evidently for the attachment of 

 the tibialis anticus. The broad groove on the anterior face of the tarso- 



