RHADINICHTHYS HIBERNICUS. U5 



total. The shape is elegantly fusiform, though the back appears somewhat unusually 

 arched, but is evidently the result o'i post-vioiiem distortion. The head is obliquely 

 crushed so that the posterior boundary of the opercular bone is not clearly defined, but 

 the branchiostegal plates of both sides are obscurely indicated, as is likewise the cleft 

 of the mouth, which shows traces of conical incurved teeth. More than this cannot be 

 said regarding the cranial structure, except that the external surfaces of the bone show 

 everywhere traces of a fine tuberculo-striate ornamentation. 



The scales appear small for the size of the fish, those of the flank being not much more 

 than Yy '"^1^ i'^ height, and rather less in breadth ; they become very small on the tail- 

 pedicle, where they are succeeded by the acutely lozenge-shaped ones of the caudal body 

 prolongation. The surface of the scales (fig. 2) is covered with closely set, delicate, yet 

 well-marked ridges or striae — wavy, sub-parallel, branching and intercalated — whose 

 direction is mainly across the scale from before backwards and parallel with the upper 

 and lower margins. I rather think that these ridges end in fine denticulations of the 

 hinder margin, but as the state of preservation is not good I cannot feel sure. It is 

 also to be noted that the scales on the belly are considerably lower and narrower in 

 form than those on the sides of tiie body. 



The fins are rather small. The impression of the right pectoral is seen just behind 

 the head. It is y^ inch in length, narrow and pointed ; distinct fulcra are seen along 

 its anterior border ; its rays are slender and apparently unarticulated for a considerable 

 distance, but owing to the state of preservation of the specimen it is difficult to say how 

 far. 



The dorsal fin is situated far back, commencing opposite a point 4 inches from the 

 front of the head ; the length of its base is a trifle less than y~6 inch, that of its longest 

 rays slightly over \ inch. Its rays are sleiuler, closely set, their articulations not dis- 

 tinctly marked; fulcra are not observable along the anterior border. 



The anal fin is larger than the doi'sal ; although its apex is not perfect, its anterior 

 rays reach a length of -Jy inch ; tlie full extent of its base is also not seen. Fulcra are 

 not visible along the anterior margin, but that does not necessarily imply their absence 

 in the species. 



The caudal is also small for the size of the fish, and is preserved up to the extremity 

 of the upper lobe, though only a portion of the lower one remains. The length of the 

 base of the caudal fin from the commencement of the lower lobe to the tip of the 

 upper one is l-^-,,- inch, which is very short for a Palseoniscid fish of the size. The rays 

 of this fin are slender and have their divisions longer than broad, but, owing to the 

 anterior margin not being preserved, no fulcra can be seen. 



Observations. — This unique specimen, representing a new and beautiful species of 

 Rhadinichthys^ is contained in the British Museum, and for the privilege of naming and 

 describing it I am indebted to the kindness of Dr. Smith Woodward, F.R.S., Keeper of 

 the Geological Department. Of its novelty there can be no doubt when we take into 



