AND OTHER EXTINCT BIRDS OE MAtJBITIUS. 



287 



and metatarsus ; secondly, the length of the " perone " or fibula, which, at least 

 in the two larger specimens, is continued far beyond the level of the tubercle 

 of the hallux attachment, as far down as the epicondyle; thirdly, the relatively 

 greater length of the peroneal crest, which in our specimens extends to the end 

 of the upper third of the tibia, while in Heliodilus it ends a little below the upper 

 fourth ; the actual peroneal connexion, /. e. the ridge of the tibia which touches the 

 fibula, is absolutely and relatively larger in our specimens than on the tibia figured by 

 M. Milne-Edwards (Grandidier, Ois. de Madagascar, plate 36 c, fig. 8). 



On the other hand, there are differences, notably the longer and higher cnemial 

 process of the tibia and the shortness of the humerus, sufficient to justify the specific 

 distinction of this Mauritian Owl from Strix Jlammea, with its numerous varieties. 



Humerus. 



I mm. 



Stris sauzieri 71 



. sp I 



• • flammea ! 84 



Heliodilus soumagnii 72 



Athene muriTora 64-69 



Asio capensis .... ■ 



Scops rutilus | 47 



Sceloglaux novae-zealandiae . '• -58 



Bubo virginianus I 163 



madasascariensis . . . . ! 80 



Tibia. 



mm. 

 90, 92, 93 



85 



87 

 09-76 



95 



50 



64 

 146 



8-2 



Metatarsus. 



Quotient 



Tibia. 



Metatarsus. 



mm. 

 63, 63, 64, 64, 66 



56 pair. 



60 

 57-00 

 41-46 



56 



28 



35 



75 



41 



, , Longest Metatarsus. 



Shortest Metatarsus. 



The pair of metatarsi measuring 56 mm. in length are at the same time much more 

 slender than the other five metatarsi. We do not feel justified in explaining this 

 considerable difference in size and strength by difference of age, because the bones 

 are fully ossified and show all the characteristic markings in the same pronounced 

 degree. Only the bony bridge over the tendon of the m. tibialis anticus is broken, 

 and was moreover certainly incomplete in both of the smaller metatarsi. We 

 naturally tried to fit the shortest tibia of 90 mm. length on to the metatarsus of the 

 corresponding side, but the tibial condylar facets are a little too large. If they fitted, 

 the quotient of this shortest tibia with the shortest metatarsus being 1*61 would 

 indicate an Owl different from any of those which are mentioned in our list. Asio 

 capensis cannot be thought of, because its metatarsus is several times stronger than 

 the two in question, nor do we feel inclined to explain the shortness and slender shape 

 of these two bones by sexual difference of Strix sauzieri. Unless we assume, what is 

 unlikely, that the island of Mauritius possessed two different species of Strix, we have 

 to conclude that the short pair of metatarsals belonged to a small individual of Strix 



