Dr. E. IJ. Traquair on a neio S/jecies o/Gji-acaiithus. 417 



The species 4, 5, 6, 7 were originally described under the 

 genus Acunthodrilus (see my article in Quart. Journ. Micr, 

 Sci. xxxii.), bur have been transferred on account of their 

 possessing two gizzards and a genital fossa. 

 October 17, 1890. 



LI. — On a new Species o/Gyracanthus. 

 By R. H. Traquair, M.D., F.R.S. 



In their recently published ' Catalogue of British Fossil 

 Vertebrata ' Messrs. ISmith Woodward and Sherborne state con- 

 cerning the spine from Burdiehouse figured by Ilibbert (Trans. 

 Roy. Soc. Edinb. xiii. pi. xi. fig. 1), and referred by Agassiz 

 to his Gyracanthus formosus, that it "is of doubtful species." 

 This spine is in the collection of the Museum of Science and 

 Art, and I had long been of opinion that neither it nor any 

 other specimen of Gyracanthus from the Calciferous Sand- 

 stone series could be referred to the same species as that from 

 the Coal-measures figured by Agassiz as such (Poiss. Foss. 

 t. iii. tab. v. figs. 2-6), and which, on the other hand, must 

 also include his G. fonnosus. Lately a considerable number 

 of Gyracanthus spines have occurred in the " Dunnet" shale 

 at Straiton, which clearly belong to the same species as those 

 from Burdiehouse, and enable one to have a still better idea 

 of its characters and configuration. 



Those spines resemble G. formosus (incl. tuherculatus) in 

 the nature of their ornament, and though most of the Burdie- 

 house specimens are eroded and worn, that figured by Hibbert 

 has the tuberculation of the ridges in places exceedingly well 

 marked. But from G. formosus the species differs in having 

 the basal or inserted portion very small, and again in the 

 usual want of that lateral curvature which is so constant a 

 feature in all examples of that species which have attained 

 any size. The antero-posterior curvature is usually present, 

 but only in one specimen out of many have I observed any 

 pronounced lateral flexure. Like G. formosus they are fre- 

 quently worn at the tips, and all are bilaterally unsym- 

 metrical. 



As there is no doubt that we have here a species which 

 has not hitherto been named or defined, I propose for it the 

 name of Gyracanthus rectus. 



Not uncommon in the Calciferous Sandstone series of the 

 east of Scotland. Besides Burdiehouse and Straiton, the 

 following localities may be noted : — Burntisland, Pittenvveem, 

 St. Andrews. 



Ann. cl; Mag. N, Hist. Ser. 6, Vol. vi. 30 



