from the NeujhbvurlioDd nf Kdinhnifjlt. 2-^) 



teeth and scales, which it is ditlicult to ()l)faiii tVoin those pre- 

 served ill the rciractory irDiistoiie of the Wardie inxhdcs. 



In his very brief notice of this fish* Agassiz stated that, 

 though very distinct as a species, its generic relations were 

 doubtful, mentioning as a reason that the scales were much 

 higher tlian broad. Having, since my previous description was 

 written, enjoyed better opportunities of studying the characters 

 of the genus Pijfjopterus^ I have found the conclusion inevit- 

 able, that Agassiz's doubts were so well founded that it be- 

 comes aljsolutely necessary to erect a new genus for the fish 

 under consideration. I propose, then, for it the generic title of 

 Nonatoptychiufi, in allusion to the fine thread-like striaj with 

 which the scales and many of the head-bones are ornamented. 



As regards the scales, these differ in a most marked manner 

 from those of Pijgopterus. In the latter genus they are 

 regularly rhoniboidal (PI. XVI. fig. G) ; and over the greater 

 part of the body they are equilateral, those in the front of 

 the flank only being rather higher than broad. The exposed 

 rhombic surface has its acute angles pointing, as usual, up- 

 wards and forwards, downwards and backwards ; the anterior- 

 superior angle is produced into a prominent point covered by 

 the adjoining scale ; while from the middle of the uj)per margin 

 a special and well-marked articular peg or spine likewise rises, 

 to be received into a corresponding depression on the under sur- 

 face of the scale above. In fact Agassiz describes the scales 

 of P. mandibular is as being very firmly articulated by means 

 of " deux cornes, qui existent au bord su])erieur de I'^caille, et 

 se logent sous la surface (^maillee de I'ecaille voisine" f. These 

 " deux cornes " (the one a production of the anterior-superior 

 angle of the scale, the other a special articular spine arising 

 from its upper margin) are indeed, as every one knows, by 

 no means specially characteristic of Pygopterus. In Nema- 

 toptychius Greenockii^ however, the scale is of a very dif- 

 ferent and, in truth, most peculiar form (PI. XVI. figs. 9, 

 10, 11). All along the back and flanks the scales are much 

 higher than broad ; the exposed area is indeed more or less 

 rhoniboidal ; but the acute angles are here the posterior- 

 superior and the anterior-inferior. The anterior-superior 

 angle is not produced into an articular point, distinct from 

 the proper articular spine, which latter, broad and triangular, 

 arises from the entire upper margin of the scale. The ex- 

 posed ganoid surface is ornamented by veiy delicate thread- 

 like, wavy, branching and anastomosing ridges, Avhich, in the 



* Poissons Fostiilfp, t. ii. pt. 1. p. 7*^. 

 t Ihid. p. 70. 



