SCOTT : LITOPTERNA OF THE SANTA CRUZ BEDS. 14I 



Metatarsal II is long and heavy ; the head is narrow, but thick, and has 

 a prominent hook-like projection from the plantar side. On the tibial 

 side, below the head, is a small concave facet for the entocuneiform. This 

 metatarsal rises far above the proximal end of mt. Ill and has an exten- 

 sive lateral bearing against the ectocuneiform by means of two facets, one 

 near the dorsal border and the other upon the plantar process. Beneath 

 the dorsal facet for the ectocuneiform is an elongate, narrow surface for 

 articulation with mt. III. The shaft is stout and trihedral, with rounded 

 borders, and the distal trochlea resembles that of mc. II, with the very 

 prominent carina extending over the dorsal face. 



Metatarsal III is somewhat longer than mt. II, but as its proximal end 

 is at a lower level than that of the latter, its effective length is consider- 

 ably greater. The head is broad and thick, ending behind in a prominent 

 plantar hook, and carries a large surface for the ectocuneiform, which is 

 convex planto-dorsally, slightly concave transversely. On the tibial side, 

 near the dorsal border, is a facet for mt. II and another on the plantar 

 hook, and on the fibular side are two facets, in corresponding positions 

 for mt. IV. The shaft is straight, slender and subquadrate, widening 

 somewhat near the distal end. The very prominent carina is plantar and 

 distal ; on the dorsal face it is very obscurely indicated, being even less 

 distinct than in the corresponding metacarpal. 



Metatarsal IV is the counterpart of mt. II, but is a little shorter and 

 heavier. A plantar hook is present, as in the other metatarsals, and the 

 irregularly convex cuboid surface extends the full depth of this hook. On 

 the fibular side of the head are two small facets for the vestigial mt. V, 

 and on the tibial side are two others for mt. Ill, the dorsal one a promi- 

 nent convexity and the plantar one circular and plane. The distal end is 

 asymmetrical, with a large rugose tuberosity on the fibular side, and the 

 carina is prominent on the dorsal face of the trochlea. 



Metatarsal V has not yet been found, but its presence and its vestigial 

 character are indicated by the facets on mt. IV and the cuboid. 



The phalanges of the pes are so like those of the manus as to require 

 no particular description. 



Restoration (PL XVI). — Of the many curious animals which make up 

 the Santa Cruz fauna, few can have had a more remarkable appearance 

 than Theosodon. In size, there is no great difference among the various 

 species so far found in the Santa Cruz formation, the best known species, 



