642 DB. P. CHALMERS MITCHELL ON THE | Dec. 17, 



iii Otis are practically identical. In Rhinochetus (text-fig. 76) the 

 distal slip (a), the median slip with its fan (/3), and the proximal 

 slip (y) are all distinct. In Ewypyga the condition is very like 

 that in Rhinochetus, the three slips and the f'nn all being present, 

 and in Hdiornis (text-fig. 78) a similar arrangement exists. 



Here again the conditions of the brevis tendon show that the 

 Gruiforines are not a closely coherent group and do not show any 

 close correlation of apocentricities. The broad, diffuse condition of 

 the tendon, little separated from the fasciae between the dorsal and 

 ventral portions of the patagium, is probably the more archeceutric, 

 and occurs in the diastataxic Gruinae and Araminae, but also in 

 theeutaxicDicholophinae. The others, eutaxicaud diastataxic, show 

 the more apocentric condition of a well rounded tendon. The 

 extent to which the proximal, median, and distal slips of insertion 

 (y, /3, and a) are developed has no correlation with the eutaxy and 

 diastataxy; the extension of the median slip (/3) to form a fan 

 reaching towards the ulnar edge of the wing is almost certainly 

 apocentric. and is absent in the diastataxic Rallida-. present in the 

 others, eutaxic or diastataxic. 



Pectoralis propatagialis.—h\ Eurypyga alone there are separate 

 slips running to the longus and brevis tendons from the pectoralis 

 major. In all the others there is a reduced slip, chiefly tendinous, 

 from the pectoralis running either to the common portion of the 

 longus and brevis or to the longus tendon alone. Possibly repre- 

 senting the brevis portion, there is present in Heliornis (text-fig. 78, 

 p. 640) one (or in individual cases two) tendinous slips stretching 

 from the edge of the humerus to the common tendon of the longus 

 and brevis. In the figure, the deltoides propatagialis muscle is 

 represented as divided and turned backwards to show these. 



Biceps propatagialis. — This muscular slip is completely absent 

 in the Otididae and Dicholophida;, an obviously apocentric modifi- 

 cation, as the slip is present in all the other members and in the 

 most nearly allied groups. Garrod (6) attached great taxonomic 

 importance to the presence or absence of this slip ; but its presence 

 appears to be an Avian archecentrie character and therefore of no 

 direct value as a guide to affinity ; its loss is an occurrence that 

 •night well have occurred repeatedly and independently. Thus 

 Fiirbringer found it absent in certain members of the Steganopodes, 

 Pelargi, Galli, Parrida?, and Megapodidae, and in individuals of Sula 

 and of Talegallu. Its loss is therefore to be regarded as what 1 

 term a multiradial apocentricity and is no direct indication of 

 affinity. 



Apart from the Otidida> and the Dicholophida?, in the other 

 members of the Gruiform assemblage the biceps slip is alwavs 

 present and arises as a bundle of fibres which, separating from the 

 biceps brachii, run outwards on to the patagium in the direction of 

 the longus tendon. The insertion displays differences. In Eury- 

 pyga and in Rhinochetus ' (text-fig. 76, B.P.) it occurs in the form 



Mr. Beddard has failed to find this is one specimen, but mentions that 

 Garrod had recorded its presence : there was no doubt about its presence in my 



specimen. 



