26 Sigurd Johnsen. 
after all, must be a Scombroid form, but “a most abnormal and 
specialized Scombroid, and that the features in which it approaches 
the Acanthuridae — the most notable of which are the restricted 
gill-openings, united pelvic bones, small number of vertebrae, 
short first vertebra, and maxillaries attached to the non-protactile 
premaxillaries, as well as the correspondence in the visceral ana- 
tomy — are to be regarded as the result of convergence.” As a 
starting point for this convergence, Regan takes the habits they 
have in common, the Acanthuridae are vegetable feeders, Luvarus 
would then be a Scombroid, which has adopted this habit. 
My opinion is that it is more likely that Luvarus is in 
many ways a primitive Scombroid, as compared to the real, mackerel 
fish (fam. Scombridae) than an abnormal and specialized Scom- 
broid. The resemblance which Luvarus, on the one hand, shows 
to Squamipinnes and, on the other, to Scombriformes may equally 
well be explained as relationship to both, as convergence to the one 
and positive relationship to the other. 
Jordan!) also assumes that there is “a line of development 
from Scombroid fishes to those called Squamipinnes.” It is, 
however, more natural to assume a development in the contrary 
direction, viz. from coast forms to pelagic ones. From the warm 
coast water forms Squamipinnes is developed on the one hard, 
and, on the other, there are forms which have taken up more or 
less pelagic habits. 
The appearance and structure of the caudal fin of Luvarus 
is of the same type as that of Scombrijormes, and judging from 
W aite’s illustration most like that of Scombridae; on account of 
the differences, which are, however, found, one might well be in- 
clined to look upon Luvarus as an abnormal, specialized Scombroid. 
But if we take into consideration characteristics such as the number of 
vertebrae and the scaly covering, the case assumes a somewhat 
different aspect. In Luvarus, the number of vertebrae is 20—22 
(according to Nardo 20, Ginther 11 +11) in the Caran- 
gidae 24—26, in the Scombridae 31—50 (Scomber scombrus 
14+ 17, Thynnus thunnus 16 +23). The scales of Luvarus are 
of a primitive type, ending in a free, elevated, flat piece; the ravs 
of the pectoral and caudal are partially covered with scales. The 
1) Jordan, D. S.: A Guide to the Study of Fishes. Vol. II, p. 292. 
New York 1905. 
