ELONICHTHYS AITKENI. 77 



Returning now to fig. 8, the pectoral fin seems here to be relatively of enormous 

 size, — passing, indeed, beyond the origin of the ventral, although it is clear that the 

 anterior part of the fin is not preserved. Distortion is probably the cause of the 

 approximation of tiiese two fins. The pectoral rays here seen are slender, and 

 dichotomise to an extreme degree of fineness ; but in one of the other fragments in which 

 the anterior rays are exhibited, these are stout and obliquely striated, but it is not clear 

 how far they are articulated. Only a portion of the ventral is shown in fig. 8, but 

 what we see of it leads us to believe that it was long-based and many-rayed, — such of 

 the rays as are seen being proportionally fine, tolerably closely jointed, and longitudinally 

 striated, though in the other fragment above referred to, and in which a portion of this 

 fin is also seen, the striae on its rays are oblique. The dorsal, as shown in our figure, 

 has the usual triangular-acuminate shape, but its rays are too badly preserved for special 

 description. Traces of the origin of the anal are seen between the ventral and the 

 caudal ; the upper lobe of the latter is preserved nearly to its termination, hut the lower 

 is cut off at the j)lace of bifurcation. All the rays seen are moderately closely jointed, 

 longitudinally striated externally, aiul minutely dichotomised. 



The form of the scales is somewhat peculiar. On the flank (figs. 10, 11) they are 

 almost rectangular, and considerably higher than broad ; the covered area is narrow, 

 while the exposed part is covered with fine, somewhat wavy ridges, occasionally 

 bifurcating and intercalated, and having a very oblique downward and backward direc- 

 tion ; in some of the more anterior scales this obliquity is very strongly marked. There 

 are no denticulations on the hinder margin. The articular spine is well developed, as is also 

 the socket on the under surface of the scale, but the keel is feeble or obsolete. The scales 

 towards the tail and the dorsal and ventral margins appear, as usual, lower in contour. 



Observations. — When I saw the first found s])ecimen of this fish the form and 

 manner of ornament of the scales strongly suggested Platysomid affinities ; but the 

 subsequent discovery of the maxilla and impression of the mandible associated with 

 these scales on the same slab clearly showed that we had to deal with a meml)er of the 

 Palajoniscidae. Then came the specimen here figured, in which the arrangement of the 

 fins is shown, and whose general resemblance to Elonichthys is so great that I j)refer to 

 include it in the genus, unless a new one is to be instituted for its reception. 



Geological Position and Localities. — From the Gilmerton Ironstone at Venturefair 

 Pit, Gilmerton, and from the Borough Lee Ironstone, Loanliead, near Edinburgh, — both 

 seams being in the Carboniferous Limestone Series of Midlothian. Also from Broad- 

 stone, Beith, in the Carboniferous Limestone Series of Ayrshire, collected by the late 

 Mr. Robert Craig. 



11. Elonichthys AiTKENi, Traquuir. Plates XVI, XVII, figs. 1 — 7. 



Elonichthys Aitkeni, Traquair. Geo!. Mag. (3), vol. iii, 1886, p. 440. 

 11 



