COMPARISON OF FAMILY CHARACTERS 



401 



and Wagner's P. brevivelis are transferred to Isopholis by Zittel, and to 

 Eugnathus by Woodward.* P. crenulatus of Egerton is retained by the 

 last-named authority among the Pholidophoridas but by Zittel is ranged 

 alongside of /. muensteri. 



Figure 2.— Head of Pholidophorus macro cephalus Ag. 



From lithographic slates of Eichstadt, Bavaria, cl, clavicle; fr, frontal; iop, interoperculum ; 

 md, mandible; mx, maxilla; na, nasal; op, operculum; pa, parietal; pmx, premaxilla ; jooj), pre- 

 operculum ; psph, parasphenoid ; pt, supratemporal ; scl, "snpraelavicle " (? post-temporal) ; so, 

 suborbital; sop, suboperculum.(after Zittel). 



Theseinstances merely emphasize the difficulties of effecting a trenchant 

 separation among similar or annectant types. Figures 1 and 2 will serve 

 to illustrate the different pattern^ of cranial structure in EugnaLhus and 

 Pholidophorus respectively, and also as a key for distinguishing the cor- 

 responding parts in plates 45-47. 



Method of preparing Illustrations used 



' Before passing to a detailed description of parts, a word should be said 

 explanatory of the illustrations. 



Plate 45 is reproduced from photographic negatives without retouch- 

 ing of any kind. The three figures show the specimens just as they were 

 found, and are very nearly of the natural size. Figure 2 shows the right 

 side of a fish preserved in counterpart, the opposite half yielding a very 

 sharp reverse impression, and employed as a groundwork for plate 46, 

 figure 2. The originals of plate 46, and of plate 47, figures 2, 3, and plate 48, 

 figure 3, are all in the form of counterpart impressions. They were first 

 photographed, and the positives printed very light on platinum paper. 

 The details were then carefully worked out in India ink with the point 

 of a brush by the well known artist, Mr J. Henry Blake, of Cambridge- 

 Figures 1, 4, and 5 of plate 47 (the last two being counterparts of the 

 same specimen) and figure 1 of plate 48 are reproduced direct!}^ from 

 phqtographs without retouching. Figure 2 of plate 48 is from an en- 



* Log. cit.i p. 301. 



