LITTLE PIKED WHALE. 269 



skulls of various ages all, however, immature (and unfortunately for the most part imperfect). 

 In addition I have reduced these to percentages of greatest breadth of the respective skulls. The 

 corresponding dimensions of a fine adult skull from Norway in the Museum of Comparative 

 Zoology complete the series, and show the difference in proportions between immature and 

 adult skulls. 



The table brings out rather strikingly: (1) the relatively slight variation of the different 

 general proportions in skulls of nearly the same size; (2) the considerable differences in the 

 same proportions when immature and adult skulls are compared. The great constancy in 

 the size of the tympanic bone, which in five skulls is of very nearly the same length, indicates 

 that it attains its full size at an early age, and does not continue to grow with the rest of the 

 skull. Since this very hard and loosely attached bone is often the only part of a whale skeleton 

 preserved in fossiliferous deposits, it is obvious that its constancy in size and shape make it 

 of much value in determining the species to which it belonged. 



Vertebrae. — The vertebral column shows much reduction over that in the other species 

 of the genus. The rib-bearing vertebrae are eleven, the lumbars twelve or thirteen, and the 

 caudals from seventeen to twenty — a total varying from 46 to 50 if all the published formulae 

 are to be regarded as correct. The usual formula is: C 7, D 11, L 12, Ca 18 = 48; this is the 

 count in the Massachusetts skeleton in the U. S. National Museum. It is possible however, 

 that one or two of the terminal caudals are often lost. A skeleton from Truro, Mass., now in 

 the Museum of Comparative Zoology, has the following formula: C 7, D 11, L 12, Ca 20 = 50. 

 The caudal vertebrae were very carefully dissected out by myself, and there is no question that 

 this was the correct number for this individual. The only other case in which this number 

 is recorded is that given by Sir William Turner for a Scotch specimen, viz., C 7, D 11, L 13, 

 Cal9 = 50. Fifty is no doubt the maximum number. 



In marked contrast to the Common Finback the upper and lower transverse processes 

 on each side of the third to fifth cervicals usually are not united at their outer extremities to 

 enclose a vertebrarterial canal, but instead, those of the axis only are so united forming a closed 

 ring. This is the condition in a skeleton (no. 7980) in the Museum of Comparative Zoology 

 from Cape Cod and in a second from Massachusetts in the U. S. National Museum. In a third 

 and younger specimen in the M. C. Z. collection (no. 8832 probably from Cape Cod) the arch 

 is complete on the left side but not quite so on the right, though no doubt it would have closed 

 later in hfe. In the third, fourth, and fifth cervicals the lower process (parapophysis) is longer 

 than the upper (diapophysis) . In the sixth, however, the upper is the longer, and in the seventh 

 it is even more extended, with a strong downward curve. The lower process practically dis- 

 appears with the seventh cervical, where it is reduced to a minute knob. In one specimen 

 recorded from Europe, the processes of the fifth vertebra unite to form a ring, and three cases 

 are recorded in which they are so united in the sixth vertebra. 



