In all these breeds the seventh pair was very small, and was destitute of processes, in which respect it differed from the same rib in the rock-pigeon. In one Tumbler, and in the Bussorah Carrier, even the sixth pair had no process. The hypapophysis of the second dorsal vertebra varies much in development; being sometimes (as in several, but not all Tumblers) nearly as prominent as that of the third dorsal vertebra; and the two hypapophyses together tend to form an ossified arch. The development of the arch, formed by the hypapophyses of the third and fourth dorsal vertebræ, also varies considerably, as does the size of the hypapophysis of the fifth vertebra. The rock-pigeon has twelve sacral vertebræ; but these vary in number, relative size, and distinctness, in the different breeds. In Pouters, with their elongated bodies, there are thirteen or even fourteen, and, as we shall immediately see, an additional number of caudal vertebræ. In Runts and Carriers there is generally the proper number, namely twelve; but in one Runt, and in the Bussorah Carrier, there were only eleven. In Tumblers there are either eleven, or twelve, or thirteen sacral vertebræ. The _caudal vertebræ_ are seven in number in the rock-pigeon. In Fantails, which have their tails so largely developed, there are eight or nine, and apparently in one case ten, and they are a little longer than in the rock-pigeon, and their shape varies considerably. Pouters, also, have eight or nine caudal vertebræ. I have seen eight in a Nun and Jacobin. Tumblers, though such small birds, always have the normal number seven; as have Carriers, with one exception, in which there were only six. The following table will serve as a summary, and will show the most remarkable deviations in the number of the vertebra and ribs which I have observed:— Rock Pigeon. Pouter, from Mr. Bult. Tumbler, Dutch Roller. Bussorah Carrier. Cervical Vertebræ 12 12 12 12 The 12th bore a small rib. Dorsal Vertebræ 8 8 8 8 Dorsal Ribs 8 The 6th pair with processes, the 7th pair without a process. 8 The 6th and 7th pair with processes. 7 The 6th and 7th pair without processes. 7 The 6th and 7th pair without processes. Sacral Vertebræ 12 14 11 11 Caudal Vertebræ 7 8 or 9 7 7 Total Vertebræ 39 42 or 43 38 38 The _pelvis_ differs very little in any breed. The anterior margin of the ilium, however, is sometimes a little more equally rounded on both sides than in the rock-pigeon. The ischium is also frequently rather more elongated. The obturator-notch is sometimes, as in many Tumblers, less developed than in the rock-pigeon. The ridges on the ilium are very prominent in most Runts. Illustration: Fig. 28—Scapulæ of Pigeons.