LESSER LING. 
525 
This opinion is untenable, for the two species are di- 
stinguished by constant characters; but the manner in 
which most of these characters develop in Molua dip- 
terygia, as far as we can decide from an examination 
of four adult specimens and without any knowledge 
of the earlier stages, shows that, from a systematic 
and genetic point of view, Molua dipterygia must be 
regarded essentially as a predecessor of the common 
Ling, though the former has evidently adopted in cer- 
tain respects a distinct direction of development from 
the common original type which we are entitled to 
assume. This appears from the following table of 
averages; which may besides serve to supplement the 
preceding description. 
Averages. 
Molua dipterygia a . 
Molua 
molva b . 
2 
specimens. 
2 
specimens. 
9 
specimens. 
o 
specimens. 
Length of the bodv expressed in millimetres 
606 
824 
319 
892 
1 
„ ,, „ base of the first dorsal fin in % of the length of the body 
7.i 
8.i 
10. G 
11.6 
2 
Distance between the second dorsal fin and the tip of the snout - ,, „ ,, „ ,, „ ., ,, 
33.2 
33.5 
39.3 
40. o 
3 
,. ,, ,, insertion of the ventral fins and the beginning of the anal fin ,, ., ., ., ., ,, ., 
24.2 
25.3 
27.7 
29 r 
4 
,, ,, ,, tip of the snout „ „ ,, ,, ,, ., „ „ „ ,, ,, ,, .. ., ,, 
41.5 
41.7 
46.7 
48.9 
5 
Length of the base of the anal fin ., ., ., ., ., ., ., ., 
40.5 
45.i 
38.i 
37.9 
6 
,, ,, ,, head in % of the length of the base of the anal fin 
40.3 
42.o 
56. g 
56.8 
7 
Longitudinal diameter of the eyes in % of the length of the snout. 
7G.2 
67.7 
61.9 
47.3 
8 
Breadth of tbe interorbital space in % of the distance between the tip of the snout and the hind extremity of 
the rnaxillaries. 
24.6 
26.o 
32.3 
39.i 
9 
Postorbital length of the head in % of the length of the base of the second dorsal fin 
10.5 
16.9 
23.2 
25.2 
10 
Distance between the second dorsal fin and the tip of the snout in % of the length of the base of this fin 
68.5 
65.3 
86.4 
87.6 
11 
Length of the pectoral fins in % of the distance between the insertion of the ventral fins and the beginning of 
the anal fin 
42.7 
41.8 
33.i 
81.6 
12 
Height of the first dorsal fin in % of the length of its base 
102.9 
101.4 
48.7 
48.9 
13 
Length of the snout in % of the length of the body 
5.8 
6.2 
7.o 
6.8 
14 
,, „ ., base of the second dorsal fin ., ,, ., ., „ ,, ,, ,, 
52. g 
51.3 
45.5 
45.9 
15 
Length of the snout in % of the length of the pectoral fins 
56.7 
59.o 
76.4 
73.8 
16 
Least depth of the peduncle of the tail in % of the length of the middle caudal rays 
42.2 
39.h 
71.5 
78.3 
17 
Height of the first dorsal fin in % of the length of the body. 
7.2 
8.i 
5.2 
5.7 
18 
Least depth of the peduncle of the tail in % of the length of the body 
2.7 
2.5 
4.8 
4.6 
19 
99 99 99 99 99 99 99 99 99 9 9 99 99 99 99 9 9 head 
14.2 
13.4 
22.3 
21.7 
20 
Distance between the tip of the snout and the hind extremity of the maxillary bones in % of the length of the head 
46.3 
46.7 
42.7 
43.8 
In the first 1 1 points of the comparison drawn 
in this table the averages run in the same direction, 
from a lower percentage to a higher or vice versa , and 
thus form an uninterrupted developmental series, the 
direction of development being the same in both species. 
In the next five points (12 — 10) the directions of de- 
velopment are different, Molua dipterygia seeming in 
these respects to have followed a distinct course f and 
to have had a special origin for its development. In 
the last four points (17 — 20) the direction of develop- 
ment is again the same, but at the origin of its course 
of development Molua dipterygia seems to be already 
further advanced than Molua molva. 
a Minimum length of the body in these 4 specimens 562 mm., maximum 828 mm. 
b r. o oi 1 f.A(\ 
The difference is to be explained to some extent, however, in points 13 and 14, by the fact that one of the specimens of Molua 
molva is 1,640 mm. long, and in several respects is an example of the not unusual circumstance that old age involves a reversion to the 
characters of youth. 
