28 THE VOYAGE OF H.M.S. CHALLENGER. 



The tarsalia were seven in number. The astragalus was a larger bone than the 

 os calcis. Its posterior process reached behind the corresponding process of the os 

 calcis, and formed the most projecting part of the heel ; it was grooved for the tendon 

 of probably the plantaris muscle. Its head passed in front of the same bone, and 

 articulated with the scaphoid and cuboid. Its inferior surface articulated with the 

 os calcis, and its superior and external lateral surface with the two bones of the leg. 



The os calcis was attenuated behind into a calcaneal - process, and articulated with 

 the astragalus and fibula on its superior, and the cuboid on its anterior surface. The 

 cuboid possessed both a plantar tubercle and a deep peroneal groove, and articulated 

 with the os calcis, astragalus, scaphoid, ecto-cuneiform, and 4th and 5th metatarsals. 

 The scaphoid was shaped not unlike the human bone, and articulated with the 

 astragalus, cuboid, and three cuneiforms. Of the three cuneiform bones the ento- was 

 much the largest, and the meso- was so small as not to be visible on the plantar 

 surface. The ecto-cuneiform had a peroneal groove on its plantar surface, and it 

 articulated with the scaphoid, meso-cuneiform, cuboid, and 2nd and 3rd metatarsals. 

 The meso-cuneiform was only seen on the dorsum of the foot, and the ento-cuneiform 

 passed so far in front of it that the 2nd metatarsal had to be prolonged both backwards 

 and inwards in order to reach it ; it articulated with the other cuneiforms, the scaphoid, 

 and the 2nd metatarsal. The ento-cuneiform articulated with the meso-cuneiform, 

 scaphoid, and 1st and 2nd metatarsals. 



The vertebral column of Lcptonychotcs measured, with the discs dried and in position, 

 1540 mm. or 5 feet, and as the skull was 237 mm. long, the length from the premaxillary 

 bone to the tip of the tail was 1777 mm. or 5 feet 9 inches. As the ossification of the 

 skeleton was so imperfect it is obvious that this seal in its adult condition must grow to 

 be a much longer animal than was the specimen above described. 



The length-breadth indices of the skulls measured in Table III., calculated on the 

 relation of the condylo-premaxillary length to the interzygomatic width, were for 

 Weddeli's Seal 59*9, and for the crania of Stenorhynchus leptonyx 49 "8 and 54 "8 respec- 

 tively, but calculated on the width behind the external meatus this index was 66 for 

 Weddeli's Seal and 51 and 53 "5 for Stenorhynchus leptonyx. These figures show at a 

 glance how much wider in relation to the length the skull of Weddeli's Seal is than the 

 other two crania. 



