. Bulletin - United States National Museum. Science. PHILIPPINE MACROUEOID FISHES GILBERT AND HUBBS. 537 the sensory canal system and thin bony septa of the head are devel- oped, this species holds a position intermediate between striatisslmus and its allies on the one hand, and longiceps and longipes on the other. The gill-membranes, which are free from the sides of the isthmus, unite, with a free fold, below the posterior margin of the orbit. The gill-rakers are arranged as in other species of the sub- genus Hymenocephalus; there are two series of 18 on the lower limb of the outer arch; thos
. Bulletin - United States National Museum. Science. PHILIPPINE MACROUEOID FISHES GILBERT AND HUBBS. 537 the sensory canal system and thin bony septa of the head are devel- oped, this species holds a position intermediate between striatisslmus and its allies on the one hand, and longiceps and longipes on the other. The gill-membranes, which are free from the sides of the isthmus, unite, with a free fold, below the posterior margin of the orbit. The gill-rakers are arranged as in other species of the sub- genus Hymenocephalus; there are two series of 18 on the lower limb of the outer arch; those of the outer series are decidedly, more crowded and smaller than those of the inner series, as they are con- fined to the restricted limits of the first gill-slit, which is only about as long as the orbit. Seven branchiostegals. The distance between the anus and the ventral base is equal to the distance from the tip of the snout to the hind margin of the orbit,. i^3 Fig. 33.—Hymenocephalus xascexs. Type. and about equal to the distance between the ventral base and the fold of the gill-membranes across the isthmus. The ventral lens-shaped organs are both round; the diameter of the posterior of the two, although about twice that of the anterior one, is but one-fourth that of the pupil (half pupil in longiceps and longipes). The few large scales retained on the side of the type bear 10 to 16 fine sharp spinules, directed backward, and arranged in quincunx order. The lateral line is rather poorly developed; it is separated from the first dorsal base by 2 rows of scales and from the front of the second dorsal by 4 rows. No denticulations on the second dorsal spine are apparent. The length of the first dorsal base is contained ( to ) times in the interval between the dorsal fins, and ( to ) times in the postorbital length of the head. The length of the weak and slender pectoral fin is contained ( to ) times in the head; the outer ventral ray, with it
Size: 2070px × 1207px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
