534 MR. GARROD ON THE ANATOMY OF STEATORNIS. [ June 3, 



in the Strigidse, whilst in the Caprimulgidse it is more developed, 

 reaching the lower margin of that hone. 



The tensor patagii brevis — a muscle very constant in its inser- 

 tion in the different families of birds, which arises mainly from the 

 superior extremity of the furcula on each side, and is inserted, after 

 running in the patagial fold parallel to the humerus, into the out- 

 side of the forearm near the elbow — in Steatornis agrees entirely with 

 that of many of the Strigidse, and differs slightly from that of the Ca- 

 primulgidse, as may be seen from the accompanying drawings (fig. 4, 

 p. 533), where, in the former, the main tendon becomes attached 

 to the extensor carpi radialis longus directly, whilst in the latter it 

 joins a second more superficial tendinous slip which runs back to the 

 outside of the elbow, much as in the Passeres. 



By placing the above-mentioned facts in a tabular form, the com- 

 parison between Steatornis and its allies will be more clearly seen. 



The semitendinosus is a muscle very constantly present in birds, 

 being absent only in the Owls, Eagles, true Vultures, Humming- 

 birds, and Swifts ; consequently its presence in Steatornis is in favour 

 of its being related to the Caprimulgidse rather than to the Strigidse. 



In endeavouring, from the facts recorded above, to form a correct 

 notion as to the exact systematic position of Steatornis, the diffi- 

 culties in the way are considerable. That it forms a family by itself 

 there is little or no doubt, as it presents pterylographical and inter- 

 nal peculiarities found in no other birds. By a process of exclusion, 

 an approximate idea of its position may be formed. The Strigidse, 

 Caprimulgidse, Coraciidse, Momotidae, Galbulidse, and Steatorni- 

 thidee all agree in possessing the following characters — two carotids, 

 well-developed eseca, a nude oil-gland, and no ambiens muscle. 

 Among these, the Strigidse differ from all the rest and resemble the 

 Eagles, in having no semitendinosus ; and the Steatornithidse are 

 equally peculiar in having no femoro-caudal muscle. In its pterylosis, 

 as shown above, Steatornis resembles the Strigidse much more than 

 any of the allied families, except that there are only ten rectrices. 

 I have not dissected Podargns ; but it agrees so closely with Copri- 

 mulgus in its pterylosis, according to Nitzsch, that it most probably 

 must be included in the same family. As Mr. Sclater has shown, 

 Podargus has no oil-gland, that organ being very small in the 

 Caprimulgidse geneially, but large in Steatornis. 



If the absence of the ambiens muscle in the Strigidse ha3 the 

 significance which I put on it, and is sufficient justification, in 



