8 Br. R. H. Traqitair — On a New Species of Elonichthys. 



the notochord was persistent, and the vertebral sheath (" Wirbel- 

 korperanlage ") unsegmented, or at most provided with weak ring- 

 shaped calcifications.^ 



This conclusion as to the condition of the vertebral axis is 

 indeed amply corroborated by the present specimen, as well as 

 justified by the general absence from the older rocks of anything 

 like calcified shark vertebrse. But in maintaining further that in 

 the majority of ElasmohrancMi before the Trias, the skeleton was 

 entirely soft, and the skin destitute of placoid scales, he has, I fear, 

 been rather hasty. The present specimen shows the presence of ex- 

 tensive calcification in all the parts of the skeleton save the vertebral 

 axis, and the skin was also provided with a well-developed coat of 

 shagreen. There is also no doubt that skeletal calcifications, and 

 also shagreen bodies, are not of such rare occurrence in Paleozoic 

 rocks as Prof. Hasse seems to imagine. Why they do not oftener 

 occur as conspicuous fossils is also very readily comprehensible, 

 though it is also probable enough that the remote ancestors of the 

 Selachii, at some period of the earth's history, were naked-skinned, as 

 well as with soft skeletons. 



Conclusion. — Accepting the fish just described as a new species of 

 Ctenacanthus, it yields us the following important facts regarding the 

 genus : — 



1. The shape of the animal was moderately elongated, with blunt 

 snout and heterocercal tail. 



2. The skin was covered with shagreen granules, mostly of an 

 ornate, ridged-pectinate character. 



3. There were two dorsal fins, each with a spine ; that of the 

 first being the longer. There were no paired spines, and the ventral 

 fin was opposite the second dorsal. The presence of an anal fin is 

 doubtful. 



4. The dentition was Cladodont. 



5. The vertebral axis was unsegmented; but there were extensive 

 calcifications in connexion with other parts of the skeleton. 



DESCEIPTION OF PLATE II. 



1. Ctenacanthus costellatus, Traq., one fourth natural size. 



2. Anterior dorsal spine, natural size. 



3. Ornamentation of one of the anterior ridges on the same spine, x 8 diameters. 



4. Detail of ridges more posteriorly situated, x 6 diameters. 



5. Eidges still further behind and towards the point, x 6 diameters. 



6. Tooth, X 4 diameters. 



7. Portion of skin, with shagreen bodies, x 4 diameters. 



III. — Description of a New Species op Elonichthys from the 



Lower Carboniferous Eocks of Eskdale, Dumfriesshire. 



By E. H. TRAauAiB, M.D., F.E.S. 



THE labours of Mr. Jex in the Eskdale fish-beds have brought to 

 light another beautiful new fish, now in the British Museum. 

 This is a Ganoid of the genus Elonichthjs, and though represented as 

 yet only by a single specimen, this is fortunately a very perfect one. 

 The length of the specimen is exactly 12 inches, but the tip of the 

 ' Das natxuliche System der Elasmobranchier, pt. i. p. 58. 



