EASTMAN: FISHES FROM UPPER EOCENE OF MONTE BOLCA. 329 



1901. Rhombus minimus A. S. Woodward, Cat. Foss. Fishes Brit. Mus., pt. IV, 



p. 607. 

 1911. Rhombus minimus C. R. Eastman, Mem. Car. Mus., Vol. IV, p. 383. 



Type. — Nearly complete fish; Paleontological Museum, Munich. 



"A very small species, attaining a length of about 10 cm. Length of head with 

 opercular apparatus contained two and a half times in the length from the pectoral 

 arch to the base of the caudal fin; maximum depth of trunk about four-fifths of 

 latter measure. Vertebrse ten to twelve in the abdominal, twenty in the caudal 

 region. Dorsal and anal fins deepest in their middle portion, the former with 

 about sixty-five, the latter with about forty-five rays; both these fins terminating 

 very close to the caudal, which comprises seventeen to nineteen rays. Small scales 

 well developed, apparently cycloid " (A. S. Woodward). 



Two additional examples of this early species of flat-fish, both of them beauti- 

 fully preserved, have been found in the material belonging to the Carnegie Museum. 

 These bear the catalog numbers 5313, and 5314 + 5314a. Affixed to the former 

 of these is an original label in unknown handwriting, stating that this is the original 

 specimen figured by Massalongo in Plate XIII, fig. 1, of the Memoir published by 

 him in 1859. 



These specimens are remarkable for the distinctness with which nearly all of 

 the fine structural characters are displayed, and yet little can be added to the full 

 and accurate description of the skeleton as given by Agassiz in his " Recherches." 

 This author gives a table showing the arrangement of supports for the dorsal and 

 anal fins with reference to the neural and haemal spines. Some variation is to be 

 noted in this respect, and one observes also that as a rule the extremities of these 

 elements are not usually in contact, as represented in the figure of the holotype 

 given by Agassiz. In both of the specimens belonging to the Carnegie Museum 

 now under discussion the first two neurapophyses are much expanded laterally, 

 delicate ribs are seen, the paired fins are well shown, and a number of minute teeth 

 may be recognized. There appears to be a dense squamation, all of the scales 

 being finely striated. 



It is interesting to note that Agassiz, in commenting on the scale-characters of 

 Pleuronectids, remarked upon their resemblance to those of Chaetodonts (Poiss. 

 Foss. IV, p. 288); and again, in the description of the genus Macrostoma {ibid., 

 p. 260), argued at length upon the close approximation between Pleuronectids of 

 the Psettus type and laterally compressed Chsetodonts like Platax. 



