110 DR RAMSAY H. TRAQUAIR ON FOSSIL FISHES COLLECTED BY 



must have measured 4^ inches. The length of the head is contained three and a half 

 times in the distance from the tip of the snout to the commencement of the lower lobe 

 of the caudal fin, and is equal to the greater depth of the body between the dorsal fin 

 and the occiput. The cranial roof-bones are marked with fine contorted and interrupted 

 strise, and a striated ornament characterises also the facial bones, namely, the maxilla, 

 mandible, and branchiostegal rays. The dorsal fin is situated behind the arch of the 

 back, and more than twice the length of the head from the end of the snout ; the anal 

 commences a little further back ; both fins are large, triangular-acuminate, with many 

 slender rays which are distantly articulated, the joints being often marked with a 

 delicate furrow close to, and parallel with, the posterior margin. The fulcra in both 

 fins are very well marked. The caudal is, as already indicated, broken off near its 

 commencement ; indications both of pectoral and ventral rays are seen at their proper 

 places, but the fins themselves cannot be described. The scales are moderate in size, 

 those on the flank showing an ornament which to some extent resembles that of the 

 scales of Elonichthys pulcherrimus from the Glencartholm beds, the exposed surface 

 being covered with closely-set fine ridges, those on the posterior-superior part passing 

 obliquely downwards and backwards, while on the anterior-inferior aspect they pass 

 nearly horizontally backwards, and parallel to the inferior margin. On the hinder 

 border of each scale these ridges end in delicate denticulations. As regards the scales 

 posterior to the region of the ventral fins, the ornament tends to become less pronounced, 

 and reduced to a set of grooves passing obliquely across the surface from front to back, 

 but the scales along the origin of the anal fin, and also of the dorsal, as seen in 

 the counterpart, are strongly ridged. All over the body the scales are singularly 

 undisturbed, so that the proportions of the fish are accurately shown. 



In PI. I. fig. 6 is represented another specimen, which, according to its scale 

 ornamentation and other details, I identify specifically with the one described above. 

 Its proportions seem, however, at first sight, rather different, the dorsal fin appearing 

 relatively further forward, the caudal disproportionately large, while the depth of the 

 body at the shoulder is considerably greater than the apparent length of the head. 

 But, on a careful examination of the specimen, it is evident that these appearances are 

 due to distortion by " shortening up," the scales of the region behind the head being- 

 confused, so that the body at this place is, as it were, " telescoped." The specimen 

 measures 4|- inches in length, but I should add on at least one more inch to express its 

 original dimensions, so that we have now before us a larger example than the previous 

 one. I figure this specimen on account of the perfect caudal extremity which it 

 displays. The fin is deeply cleft and inequilobate, the prolongation of the body axis 

 along the upper lobe being proportionately stronger than in the type species of the 

 genus (Rh. ornatissimus). 



Still another specimen exists in the Survey Collection, but less perfect than either 

 of the two examples described above. It is also shortened up in a manner somewhat 

 similar to that noticed in the second one. 



