COMMON FINBACK WHALE. 189 



The dorsal vertebrae have high spines which cuhiiinate in size at the fore part of the 

 trunk. The first four incHne sHghtly forward, a few are then straight, and the remaining 

 dorsal spines have a slight backward tendency. The transverse processes arise from nearly 

 the wliole length of the centrum; the anteriormost are from the upper part of the centrum, 

 rather stout, and elliptical in section, ending bluntly with articular surfaces for the attach- 

 ment of ribs. Passing posteriorly, these processes become more flattened and broader, widely 

 expanded distally. At the same time they arise successively lower on the centnun till on the 

 lumbars they are below the level of its middle. 



The neural spine decreases in size on the lumbar and caudal vertebrae, and last appears 

 on the 52d vertebra in the Society's specimen, and on the 50th and 51st respectively in two 

 from Cape Cod (True, 1904). The last trace of the transverse process is on the 49th vertebra 

 in the Gloucester skeleton and on the 48th in one from Cape Cod in the U. S. National 

 Museum. The first perforated transverse process (diapophysis) is on the 45th and 43d ver- 

 tebra respectively in these two skeletons. 



In the mounted skeleton from Gloucester, the rapid tapering of the terminal vertebrae 

 is rather striking. The last one of all is practically round, somewhat flattened from front 

 to back, about 0.87 inches in diameter and 0.62 inches long. Measurements of the vertebrae 

 are given in detail for this specimen by Dwight (1872, p. 214). 



The chevron bones come one between each two caudal \'ertebrae, except the terminal three 

 or so. They are roughly V-shaped, the first one small, the second much larger, and those 

 following form a decreasing series. On account of the small size of the terminal ones, which 

 are more or less cartilaginous in immature individuals, it is difficult without special care to 

 be certain of the exact number. Hence it is that museum specimens are often incomplete in 

 respect to these bones. There are but sixteen preserved in the Society's mounted skeleton 

 from Gloucester. Van Beneden gives twenty-one as the number in a European specimen 

 specially dissected by himself. 



The ribs, as previously noted, are fifteen or sixteen" in number. Probably sixteen is the 

 normal series, with the last one of all a small floating rib, imbedded in the flesh and but loosely 

 attached to the vertebra. Where fifteen are recorded, it seems likely that this small rib has 

 been overlooked. A very interesting anomaly is occasionally found, in the shape of a two- 

 headed first rib. Tliis character was made by J. E. Gray the chief basis for his genera Sib- 

 baldius and Hunterius, but Sir William Turner (1871) showed that, as in man, this bifurcated 

 rib represents two fused ribs, of which the first is a cervical rib, articulating with the trans- 

 verse process of the seventh or last neck vertebra, and the second is the normal first rib, articu- 

 lating with the first dorsal vertebra. The articulating heads of such anomalous vertebrae 

 lie at different angles to the main shaft of the rib. All the ribs are joined to their respective 

 vertebrae by a single articulation at the end of the transverse process of the vertebra. This 



