SCALES AND DERMAL TEETH OF SOME GANOID AND PLACOID FISH. 473 
snout of the recent Sword-fish, the creature must have proved, in no small degree, 
formidable to its congeners. 
In all its details, the structure corroborates the conclusion arrived at in the pre- 
ceding memoir, and shows not only a process of growth by the addition of lamellae, 
similar to that already described, but also indicates further, that whatever may be 
the direction and distribution either of kosmine or lepidine tubes, the additions to 
the structure which they permeate are always made to the surface on which their 
largest apertures open ; whether that surface be found in an internal cavity, as in 
Megalichthys and Diplopteriis, or whether it is in their exterior, as in Ccelorhynchus. 
Description of the Plates. 
PLATE XL. 
Fig. 1. Vertical section of a scale of Lepidosteus osseus, parallel with the lateral line 
of the fish. Magnified 8 diameters. 
Fig. 2. Vertical section of the half of a similar scale, made at right angles to the 
lateral line. Magnified 14 diameters. 
Fig. 3. Vertical section of the anterior border of a scale of Lepidotus semiserratus, 
parallel with the lateral line. Magnified 25 diameters. 
Fig. 4. Horizontal section of the upper surface of part of the same scale. Mag- 
nified 112 diameters. 
Fig. 5. Horizontal section of a tubercle from the surface of a scale of Dapidius 
granulosus. 
Fig. 6. Vertical section of the same. 
Fig. 7- Horizontal section of part of the surface of Palceoniscus comptus. Mag- 
nified 90 diameters. 
PLATE XLI. 
Fig. 8. Horizontal section of part of the surface of Palceoniscus Beaumontii. 
Fig. 9. Vertical section of a scale of Seminotus rhombifer, made parallel to the lateral 
line. 
Fig. 9*. Vertical section of a scale of a Gyrodus from Kellheim, parallel to the lateral 
line. 
Fig. 10. Vertical section of Aspidorhynclius acutirostris, parallel to the lateral line. 
Magnified 16 diameters. 
Fig. 11. Vertical section of part of a scale of Acipenser Sturio, parallel with the lateral 
line of the fish, and midway between the centre and the lower angle of 
the lozenge-shaped scale. Magnified 7 diameters. 
Fig. 12. Vertical section of a scale of Platysomus parvulus, parallel with the lateral 
line. Magnified 80 diameters. 
