1898.] 



OSTEOIiOGT OF THE IMPENTOIS. 



981 



primitive, completely separate metatarsals on the one hand, and the 

 highly specialized " cannon bone " on the other, where the three 

 metatarsals are all merged to form a single shaft. 



The total length of the tarso-metatarsus is about one-fourth that 

 of the tibio-tarsus. The hypotarsus is simple, consisting of an 

 ecto- or an eeto- and entocalcaneal ridge, but they are never more 

 than low prominences. 



The tibio-tarsal shaft is perfectly straight, and about one-fifth 

 longer than the fibula. Eeto- and entocnemial crests are well- 

 developed in the adult, but there is no trace of them in the 

 half-grown C. catarrhactes from which this description was 

 taken. 



The shaft of the femur is very thick, its length about twice that 

 of the tarso-metatarsus. Like all the other bones of the leg, it is 

 non-pneumatic. 



ix. SuilMAEY. 



Mr. Grant (10) and I both find it necessary to divide the 

 Order Impennes into 6 genera {cf. p. 982). Of these, Eudyptula 

 appears to represent the least specialized form of the whole group, 

 and probably lies nearest the ancestral stock. The diagram 

 (fig. 2) is intended to express, as nearly as may be, the possible 

 relationship of the various genera one to another. As has been 

 already pointed out by Gadow (7) and Beddard (1), the group as 

 a whole seems to be most nearly related to the Tubinares. 



Fig. 2. 



f^^OJi 



/efTOC^^-i 



Diagram showing the probable relationships of the various genera 

 of the Family SpheniscidEe. 



I am unable to distinguish the skeleton of Catar-rTiactes pachy- 

 rhynchus from that of C, clirysocome. C. sclatei-ianA. C. schlegeli are 

 not yet represented in the collection of skeletons. Skeletons of 

 Spheniscus humholdti and /S. mendiculus are also wanting. 



