120 Part ITI.—Twenty-fourth Annual Report 
case of the ventral and pectoral fins the most dorsal ray—ain the case of 
the first dorsal fin, the most anterior ray—to the tip of the longest ray. 
HeIcutT or THE LATERAL LINE ABOVE THE LaTERAL Axis.—The lateral 
axis is here taken as coinciding with the straight posterior part of the 
lateral line. This line was continued by a thread on the measuring board 
along the fish, and the interval between it and the lateral line was 
measured at two points—viz., at the level of the anus and at the level of 
the base of the pectoral fin. In duscus, in place of the measurement at 
the pectoral fin, which is very close to the anus, a new point at the 
* middle of the first dorsal fin was chosen. 
LenctH oF THE Rami or Tari-Fin.—That is, the distance from the 
base of the first fin-rays of the caudal fin on the dorsal or ventral line of 
the body to the tip of the ramus of the tail. 
THE SPREAD OF THE Tatt.—The greatest breadth of the tail-fin. For 
the purpose of this measurement it is not spread out to its fullest extent, 
but is allowed to fall on the table. 
LrenetH or THE CaupaL Prepuncie: dorsal.—The part of the dorsal 
edge between the end of the third dorsal fin and the beginning of the 
caudal fin. 
GREATEST HeiGHT oF THE UNpaAIRED Fins.—The fin is stretched out, 
and its greatest breadth is measured, 7.e., between the base and the highest 
point vertically above the base. This is a character which it is often im- 
possible to get, owing to the fact that in trawled fish the fins are usually 
frayed or broken. 
The above measurements of the eye, interorbital space, of the fins, and 
of the height of the lateral line were made by means of dividers. 
THE Distance oF DIFFERENT POINTS FROM THE ANTERIOR TIP OF THE 
Fisu.—The anterior tip of the fish is in J/usews and minutus the tip of the 
upper jaw, in esmarkii the tip of the lower jaw. The distance of each 
point was measured as projected on the lateral axis. The lateral axis is 
the line joining the anterior tip to the middle rays of the tail-fin. 
These points are :— 
Anterior edge of the orbit (for the length of the snout). 
The base of the first fin-ray of the ventral fin. 
The base of the first fin-ray of the pectoral fin. 
The opercular cleft. 
The hindmost part of the edge of the operculum. 
The anus. 
Beginning and end of each of the unpaired fins. 
Beginning of the caudal fin, dorsal and ventral. 
Tip of the ramus of tail, dorsal and ventral. 
Point where the lateral line begins to rise up off the horizontal—the 
anterior end of the straight part of the lateral line. 
The beginnings of the fins were marked by means of pins inserted at 
the base of the first ray. A pin inserted in the anus was taken as the 
position of the anus. A pin lying in the opercular cleft indicated that 
oint. 
For the purpose of these measurements a measuring board, similar to 
that which was used during the research on the ‘‘ Mackerel of the East 
and West Coasts of Scotland” (Highteenth Annual Report of the 
Fishery Board for Scotland, Part III, p. 295), was employed. The 
measurements made on the soft body of the fish are not such as permit of 
exact determination, and probably the errors due to the want of rigidity is 
greater in small fish than in large specimens. There is, however, 
