[39] MATERIALS FOR A HISTORY OF THE SWORD-FISHES. 327 
would bring about a considerable increase in weight. That this is the 
case is clearly shown by the testimony of the fishermen, who say that in 
the spring Sword-fish are thin, growing fatter and heavier as the season 
goes on. 
Dr. Liitken and Dr. Giinther have lately made some exceedingly inter- 
esting observations upon the young of the Sword-fish and of the Spear- 
fish and Sail-fish. A translation of Dr. Liitken’s paper, furnished by 
Dr. T. H. Bean, is given in the Appendix (paragraph 64). 
Dr. Giinther’s studies were made upon very small specimens of unde- 
termined species, belonging to either Tetrapturus, Histiophorus, or both. 
In his latest work, “The Study of Fishes,” he summarizes the facts 
observed by him as follows: 
‘The Sword-fishes with ventral fins (Histiophorus) belong to the Tele- 
osteans of the largest size. In young individuals, 9 millimeters long, 
both jaws are produced and armed with pointed teeth, the supraorbital 
margin is ciliated, the parietal and preoperculum are prolonged intolong 
spines, the dorsal and anal fins are a long fringe, and the ventrals make 
their appearance as a pair of short buds. When 14 millimeters long the 
_young fish has still the same armature of the head, but the dorsal fin 
has become much higher, and the ventral filaments have grown to a 
great length. At the next stage, when the fish has attained to a length 
of 60 millimeters, the upper jaw is considerably prolonged beyond the 
lower, losing its teeth, the spines of the head are shortened, and the 
fins assume nearly the shape which they retain in mature individuals. 
“ Young Sword-fishes without ventral fins (Xiphias) undergo similar 
changes, and, besides, their skin is covered with small, rough excres- 
cences, longitudinally arrayed, which continue to be visible after the 
young fish has attained the form of the mature in other respects.” 
Dr. Liitken’s description of the young Sword-fishes ts an exceedingly 
valuable contribution to knowledge. 
I have collected together, in the plates which accompany this paper, 
the various published figures of young Sword-fishes, and have had them 
redrawn as nearly as possible to a unifdrm scale. 
Of the Sword-fish, Xiphias gladius, two figures are given. One, taken 
from Liitken’s “‘Spolia Atlantica ” (pl. ii, fig. 10), is 37 millimeters long ; 
the other is a reproduction of the often-copied figure in Cuvier and 
Valenciennes’s “Histoire Naturelle des Poissons” (pl. cexxv), 12 to 18 
inches long. Liitken had a smaller specimen, 10 millimeters long, but 
it was too poorly preserved to be figured. 
Of the various species of Tetrapturus and Histiophorus, six figures are 
given. The smallest is that from “ Spolia Atlantica” (pi. ii, fig. 11), and 
is of a fish 54 millimeters long. Liitken remarks that he has a series 
‘from 54 to 12 millimeters long which differ very little from each other. 
The next in size is copied from Giinther, and is probably about 10 milli- 
meters long; the third, also from Giinther, is 14 millimeters long.  Liit- 
ken has another link in the series, a specimen 21 millimeters long, which 
