21 



to the curve of the lateral margin. Enlarged scales also occur behind the dorsal fin and are 

 continued back on the upper lobe of the tail, with a much increased overlap, to its termination. 

 They diminish in size as they pass backward, and are much reduced in breadth, resembling 

 large fulcra. In advance of the anal fin and between it and the caudal, a few enlarged scales, 

 similar in shape and sculpture to those of the dorsal row, are also present. There appear to 

 be three in advance of the anal fin and about the same number behind it. All the fin rays are 

 jointed throughout, except the principal anterior ones of the pectoral pair, which appear to 

 be entire prdximally, and to be jointed only in their distal halves. They subdivide distally 

 and have the appearance of being at times slightly striated in the direction of their length. 

 Minute fulcra are present on the margin of the lower caudal lobe and on the anterior margins 

 of the other fins. The head bones are ornamented with longitudinal ridges and tubercles, and 

 transitions between the two. Figure 1 of plate III gives an attempted restoration of Rhadinich- 

 thys alberti, twice the natural size of the average specimen, based on the type material and the 

 many specimens contained in the Geological Survey collections. Figures 2 and 3 of the same 

 plate are reproductions of photographs of two individuals, collected by Dr. R. W. Ells, in 1907, 

 from which a fair idea of the general proportions of the fish and the position of its fins can be ob- 

 tained. The size of the restoration does not admit of a proper representation of most of the 

 finer details of structure and ornamentation, such as the surface sculpture of the head-bones, 

 the striation and serration of the scales, the articulation and subdivision of the fin rays, etc., 

 so that these have been wholly or in part omitted. The ornamentation of the scales is given 

 in the more enlarged figures 4, 5, and 6 of plate III. In the specimen reproduced in figure 3, 

 plate III, the position and size of the maxilla, mandible, and eye are well suggested, but in the 

 many specimens examined the bones of the head cannot be satisfactorily made out. In a number 

 of examples the obhquity of the posterior outline of the opercular apparatus is clearly indicated. 



The type specimen of Rhadinichthys alberti, No. 1960 of the Museum of Comparative Zoology, 

 Cambridge, the original of Jackson's figure 1, plate I, is imperfect in many respects. The dorsal, 

 anal, and caudal fins are but partially preserved, while the other fins, as well as the head, are 

 missing. In most of the scales the finer details of ornamentation are obscure, and the posterior 

 margins are broken. Although the scales are not, as a whole, well preserved, yet, some of them, 

 well forward on the flank, on close examination, show that the same style of striation exists 

 in them as in the type of R-. cairnsi. The principal character apparently relied on, as a dis- 

 tinguishing one between this species and R. cairnsi, was the implied difference in the scale 

 sculpture. Any difference in the ornamentation of the scales in these species, as throughout the 

 Palffioniscidse as a whole, may be expected to be most accentuated in the flank scales for some 

 little distance back from the head. The scales of R. alberti were evidently regarded by Dr. 

 Jackson as being smooth, as in the original description they are referred to as being "brilliant," 

 no other reference being made to their ornamentation beyond the observation that the posterior 

 margins are serrated. The scales of the type specimen of R. cairnsi are well preserved, with 

 the sculpture particularly definite, plate III, fig. 4. In Jackson's description they are stated 

 to be "distinctly striated parallel to anterior and lower margins," a description that, to be 

 complete, needs some reference to the coarse, oblique stria? which are present in the upper back 

 portion of the scale surface. To the writer the striation of the scales appears to be the same in 

 both species, poorly preserved in the type of R. alberti, but very clearly shown in the type of 



