146 MR. W. p. PYCEAFT OX THE OSTEOLOGY [Feb. 20, 



while by the ossification of the tendinous tissue overlying them a 

 bony roof to the pelvis is formed, which is most complete in Pitta 

 (see p. 151). 



In Fitta the fourth postsacral forms a part of the synsacrum, 

 although it really lies well behind the embrace of the innominate ; 

 on the other hand, in Xiphocolaptes, for example, the fifth free 

 caudal lies within this embrace, yet remains free. 



Well-marked intercentra, as might be expected, occur in the 

 DendrocolaptinjB — 5 to 7 vertebra; ; they are smaller in the Synal- 

 laxina; and Formicariinse, and vestigial or wanting in the Pipridse 

 and Philepittidas. 



The ventral aspect of the synsacrum is marked in a way which 

 deserves some notice, inasiiuch as it may be either deeply 

 orooved or pitted, after a fashion appai-ently not met with outside 

 the groups in which these peculiarities occur. 



Thus in the Pipridse the ventral aspect of the synsacrum is 

 marked by deep grooves extending on either side of the middle 

 line from the level of the first lumbar to the saci'al vertebrae ; 

 Avhile in Pipra there will be found a double row of deep oblong 

 pits, one along either side of the middle line, from the last 

 thoracic vertebra (the synsacral) to the first sacral. _ Among the 

 Synallaxinfe, 8ip>tornis agrees with Chiroxiphia, while Synallaxis 

 ao-rees with Pipra. The Hylactin^e have a grooved synsacrum. 

 *' These pittings appear, indeed, to occur only in thePipridpe, 

 Synallaxina;, and Acanthidosittidse, and may extend, as in Pipra, 

 along the whole length of this complex as far as the first sacral, 

 or may occur only from the last lumbar to the first sacral, as in 

 Cindodes. 



iv. The Ribs. 



In the Pipridag, Pittida?, Philepittidse, Conopophagidfe, and 

 Formica] -iin a?, long styliform ribs are borne by the cervical 

 vertebrae, from the 5th to the 9th inclusive; from the 10th-12th 

 the style is vestigial and a narrow pleurapophysial lamella alone 

 is left. The Dendrocolaptina? difier in having the styliform 

 portion of the rib much shorter than in the types just referred to. 

 Among the Synallaxinse it would seem that two types of ribs 

 obtain, one i-epresented by a band-like pleurapophysial lamella, 

 and one in which this is very broad, and may further have a short 

 style as in Xipihorhynchus. 



There are thi-ee cervico-thoracic ribs, the 1st greatly reduced ; 

 the 3rd bears an uncinate process but no sternal segment. 



There are six thoracic libs, of which five generally articulate 

 with the sternum. In some of the Synallaxinse and Dendro- 

 eolaptinte there is a tendency for the 5th rib to lose its connection 

 with the sternal border. The 6th rib, almost invariably articulates 

 with the sternal segment of the 5th, being attached by ligament 

 to a more or less well-defined facet. 



The uncinates are generally moderately long and slender, only 

 in Pitta are they conspicuously broad. 



