496 Dr. R. H. Traquair on Harpacantlius. 



was also due. Tliis specimen having been presented by 

 Mr. Anderson to the Edinburgh Museum of Science and 

 Art, I am now in a position to saj a few words as to its 

 characters. 



On comparing this spine with Mr. Stock's figure {op. cit. 

 pi. vii. fig. 1) there can be no hesitation as to identifying it 

 with his Tristychius fimhriatus. It is 2 inches in length by 

 about g- inch in antero-posterior diameter at the thickest part 

 (about the middle), and presents a strong backward curvature, 

 though not quite so strong as in Mr. Stock's specimen ; and 

 it may also be noted that the bend takes place nearer the 

 middle of the spine. Above the base the posterior margin of 

 the spine is rounded, the anterior rather sharp ; the sides are 

 flattened, and beyond the curve show a longitudinal shallow 

 groove, the surface all over being perfectly smooth and desti- 

 tute alike of the coarser ridges and more delicate stria? of 

 TristijcJdus. A considerable amount of the substance of the 

 basal extremity of the spine is lost by being broken away ; but 

 what remains, along with the excellent impression, shows that 

 there was no posterior sulcus — that the basal extremity was, in 

 fact, solid ; a pulp-cavity is very soon seen extending towards 

 the apex. Furthermore there is no posterior area ; but about 

 y^ inch from the inferior extremity there is a small rounded 

 backward projection, beyond which again, and commencing /j 

 inch from the bluntly rounded apex, the rest of the posterior 

 margin is occupied by a series of nine strong recurved denticles, 

 which are in this specimen clearly seen to form one median 

 row. 



It is therefore not only clear that the spine described by 

 Mr. Stock as Tristychius fimhriatus cannot possibly be 

 referred to Tristychius^ but that it also displays peculiarities 

 which remove it still more widely from that genus, and such 

 allied forms as Ctcnacanthus, Hyhodus^ &c., than might have 

 been supposed ; for not only is the posterior area wanting 

 and the row of denticles a single one, but the base is alto- 

 gether different in not presenting the spacious liollow or 

 sulcus open posteriorly. The occurrence of the second speci- 

 men shows also that the posterior curvature is natural and not 

 the result of accident or disease. 



It is, however, clearly a Selachian appendage ; more I do 

 not at present say regarding it. So far, however, as I am 

 aware, it does not seem to have been hitherto generically 

 recognized, and I therefore propose for it the term Harpa- 

 catithus^, so that the name will now stand Harpacanthus 

 fimbrtatus, Stock, sp. 



* cipnT), a sickle, aud uKavda, a spine. 



