ELONICHTMYS STRIOLATUS. 69 



unusually distant. The scales are proportionately small in size and delicately ornate, 

 but tiie pattern is essentially that of the general Bobisoni type. By Agassiz the rays of 

 the dorsal fin are described as being " tous bil'urques a plusieiirs reprises jusque vers leur 

 milieu;" but to my observation the dichotomisation of the longer rays, as is usual in this 

 genus, does not commence till towards their terminations. He also describes the surface 

 of the scales as being " ornee de petites rides saillantes, disposees a pen pres conin)e les 

 lignes d'accroissement en losanges concentriques plus ou nioins regulieres et un peu 

 obliques, de telle sorte que leurs angles aigus sont tournes vers les angles superieur- 

 anterieur et inferieur-posterieur de chaque ecaille," — a description which is hardly 

 correct, as there are no striae which are parallel with the posterior margin of the scale. 

 The scales of the original specimen are, however, in a very bad state of [)reservation, the 

 exterior ganoine layer having everywhere disappeared. 



Distinct though the characters of the fin-rays in this form may appear to be, a series 

 of specimens in my collection, from the oil shales of Pumpherstou, to the west of Edinburgh, 

 seem to me to dispose of the claim of nemopterus to the rank of a species, as the fin-rays 

 in these examples, though mostly fine, are very variable as regards the length of their 

 transverse joints. 



D. Variation teninserratiis. — In 1879 I described .is Ehnichlhys fejiuiscrraliis an 

 imperfect fish from the oil shales of West Calder, in Midlothian. The specimen is here 

 represented on PI. XI, tig. 4. The salient points here were the large proportional 

 size of the scales, the extreme fineness of the serration of their posterior margins, and the 

 great delicacy of their sculpture, which was nevertheless conformal)le to that in the 

 Robisoni type. The t'acial hones were also closely striated. 



Firmly convinced, as I was at the time, of the validity of " ienuisfriatus" as a 

 species, the increase of material afterwards convinced me that all the characters mentioned 

 shade imperceptibly into those of other variations of Elonichthi/s Robisoni, and in 1890 

 I accordingly abandoned it as a " good " species. The s])ecimen in question belonged 

 to Mr. Thomas Stock, from whom the counterpart was acquired by the Edinburgii 

 Museum. 



v.. Variation Diinsii. — The name Eloniclithys Dunsii was also given by me in 1879 to 

 a fish from the oil shales at Broxburn, West Lothian, in the museum of the New College, 

 Edinburgh, and lent to me by the Rev. Professor Duns of that institution ; it is repre- 

 sented in PI. XI, figs. 1 — 3. The fish itself (fig. 1) is somewhat deeply fusiform, with 

 scales of moderate size and rather large median fins, while in general aspect it resembles 

 the form wiiich I had previously designated " intermedius.'"' The [)oints which \nainly 

 induced me to consider it as a distinct species were the extremely delicate serration of 

 the posterior margins of the scales (fig. .2), as in " tenuiserratus^'' and more especially 

 the fine oblique denticulation of the posterior margins of the joints of the dorsal and anal 

 fin-rays (fig. 3), which are otherwise much as in " intermedius!' Though this [)eculiar 

 serration of these fin-rays is, so far as my experience goes, unique in the geiuis 

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