502 EDWIN S. GOODRICH. 



to allow of the histology being described. But it is a very- 

 interesting and important form^ since its lepidotrichia are 

 provided with proximal unjointed buried segments longer 

 than those of any other Teleostome I have seen. The rays 

 are very numerous and very slender. The whole of the long 

 proximal segment was doubtless covered over by the body- 

 scales, and must have overlapped the endo-skeletal rays to a 

 considerable extent. The caudal fin of Holoptychius has been 

 figured by A. Smith Woodward (42). 



Osteolepis, Diplopterus, Glyptolepis, and Holoptychius re- 

 present so many stages in the development of the lepidotrichia. 

 In which direction the evolution has progressed, whether 

 from the rays with short superficial proximal segments to 

 those with long deeply buried proximal segments, or vice 

 versa, is a difficult point we shall have to discuss later (p. 509). 



Coelacanthidae. — The dermal fin-raj^s of these fish have 

 been described by Huxley (20), Reis (30), and other writers. 

 It is well known that in the remarkable upper and lower 

 lobes of the large caudal fin (not in the median lobe ?) the 

 dermal rays are regularly related to the endo-skeletal fin- 

 supports, one pair to each, as in the higher Actinopterygii. 

 Since the endo-skeleton of the other fins is not well preserved 

 it is not possible to find out the exact relations of the dermal 

 rays to the endo-skeleton, but they were almost certainly 

 different. The dermal rays themselves are well-developed 

 lepidotrichia, unbrauched, and with a long proximal pointed 

 segment overlapping the endo-skeleton (fig. 65 a), The joints 

 ill the distal region are very numerous, and very short and 

 broad. Whilst the body-scales which cover the unsegmented 

 region are provided with peculiar narrow spines, similar 

 spines are found on the segments of the jointed region of the 

 rays, and especially all along the edges of the fins (figs. 65 a 

 and b). The spines must not be confused with the very 

 similar fulcral scales of the Actinopterygii (fig. 54). They 

 are not modified scales like the latter, but denticles of dentine, 

 with perhaps a coating of enamel, homologous with the small 

 denticles on the scales and dermal rays of Lepidosteus. 



