BRITISH FOSSILS. 



Decade IX. Plate IX. 



MEGALURUS AUSTENI, 



[Genus MEGALURUS. Agassiz. Sub-kingdom Verebrata. Class Pisces. Order 

 Goniolepidoti. Eamily Sauroidei. Sub-family Sauroidei homocerci. 2nd Group ; tail 

 more or less rounded.) Caudal fin very large and rounded ; dorsal fin opposed to the 

 interspace between the ventral and anal fins ; head large ; jaws furnished with large 

 conical teeth, intermixed with smaller ones ; vertebral centres ossified.] 



Megalurus Austeni, Sp. Nov. 



BescriiDtion. — The discovery of the very perfect specimen de- 

 scribed in the preceding article has furnished the clue to the true 

 nature of a group of icthyolites not uncommonly occurring in 

 the quarries of Purbeck stone at Swanage, but for the most part iti 

 a very fragmentary condition. Many of these specimens have come 

 under my notice from the collections of Mr. Austen and others, vrho 

 have turned their attention to the Purbeck fossils ; but I have 

 hitherto failed to recognize them as belonging to the rare genus 

 Megalurus of Agassiz. The parts most commonly preserved are 

 the vertebral column and some of its spinous appendages, and such 

 specimens have generally been considered as belonging to the • 

 Lepidotus minor, so common in the Swanage quarries. Last year I 

 obtained a specimen, more perfect than any I had before seen, of 

 this fish, but as the tail, so characteristic of the genus was deficient, 

 I passed it over without a detailed examination, in the hopes that 

 more satisfactory evidence of its generic affinity might be brought 

 to light. While examining the specimen described in the last 

 article, and comparing it with other specimens, I became aware of 

 the affinity between it and the Swa^nage specimens, a result which 

 subsequent investigation proved to be correct as to general relation- 

 ship, the species, however, being distinct. The portion of the fish 

 preserved in the specimen comprises about two-thirds of the entire 

 length, the hinder third being deficient. The pectoral, ventral, and 

 dorsal fins are seen in situ, but the anal fin is wanting. The 

 fish, when entire, would probably measure ten or eleven inches in 

 [IX. ix.] 9 k 



