82 J. H. ORTON. 
from that in Sample III. In this sample (IV) it was decided to include 
under “ well-developed ” open hemal arches those in which the heemal 
processes were relatively stout to those of the first closed arch, but which 
processes did not necessarily possess the trace of a cross-piece on their 
internal faces. This change of recording has resulted in only a slight 
difference in the records, but in a few cases the number of vertebrz 
Fic. 6.—Pectoral Fin. 17 rays. 
y) 
recorded in the “a” category is higher than in corresponding skeletons 
in Sample IIT. 
It should be mentioned that in some skeletons the hemal processes of 
the vertebre anterior to the first vertebra with complete arch were 
missing, having been cleaned away ; in these cases the following mark 
is placed alongside the record. 
EXPLANATION OF THE RECORDS OF CHARACTER 18 
IN SAMPLES II, III, AND IV. 
The number of vertebree given in column 18 is the number of vertebree 
between the skull and the ossicle marked B in Fig. 2. It may be re- 
iterated that the ossicle marked B in the figure is no¢ included in the total 
given. Remarks on abnormalities or noteworthy features of particular 
skeletons are connected by an asterisk to explanations in the Appendix 
to the Tables. It may be noted that in several skeletons two or more 
vertebrae have apparently become fused together; as, however, such 
fused vertebree show uniformly only two articulations, they have in each 
case been counted as one vertebra, although it is most probable that 
most of these abnormal vertebra are equivalent to two or more normal 
ones. Each case is discussed in the Appendix to the Tables. 
EXPLANATION OF RECORDS OF CHARACTERS 1 TO 9, 
11, 12, 15, AND 16 IN SAMPLES III AND IV. 
Characters 11 and 12 call for little comment. 
In counting the keeled scales between the pelvic fin and anus (11) the 
adjacent scales were cleaned well away before beginning to count. In 
