. The Annals and magazine of natural history; zoology, botany, and geology. g ridgesremain. Although Agassiz did not enter quite so much into detailin his description, yet the leading characters of the genus were • Ann. & Mag. Nat. Hist. (5) xiii. p. 41. Dr. R. H. Traquair on Harpacanthus. 495 very well grasped by him in his definition of Tristi/chius, andhe lays particular stress upon the presence of the three longridges, on which he in fact founded his generic name. But ifwe compare Agassizs figure of T. arcuatus with that of ^s ^^Tristi/cJiius^^ Jimhiatiis, it will be apparent that
. The Annals and magazine of natural history; zoology, botany, and geology. g ridgesremain. Although Agassiz did not enter quite so much into detailin his description, yet the leading characters of the genus were • Ann. & Mag. Nat. Hist. (5) xiii. p. 41. Dr. R. H. Traquair on Harpacanthus. 495 very well grasped by him in his definition of Tristi/chius, andhe lays particular stress upon the presence of the three longridges, on which he in fact founded his generic name. But ifwe compare Agassizs figure of T. arcuatus with that of ^s ^^Tristi/cJiius^^ Jimhiatiis, it will be apparent that thetwo forms have hardly that amount of resemblance which wouldwarrant reference to a common genus. Agassizs Tristychiusis eminently ridged and striated—Mr. Stocks spine is per-fectly smooth. The former is gently curved and tapering,and shaped generally like tlie spine of Hyhodus; the latteris nearly as thick at the extremity as at the middle, andshows, moreover, a very peculiar sudden backward this curve Mr. Stock attaches very slight importance, Fi- Fig. 1.—Harpacanthus fmhriatus, .Stock, sp. Here the greater part of the spme is seen only in 2.—The other side or counterpart of the same specimen, containing more of the actual spine, but wanting the impression of the distal extremity, which has splintered off. remarking also that it is possibly due to disease ; and hehas also given a restoration of the spine, in which he hasto a large extent straightened it out, so as to make it lookrather more like that of the genus in which he has placed second specimen of the same spine has, however, subse-quently been found in the same locality by Mr. W. Anderson,now of the Geological Survey of New South Wales, to whom,along with Mr. W. Tait Kinnear, the discovery of the first 496 Dr. R. H. Traquair on Harpacantlius. was also due. Tliis specimen having been presented byMr. Anderson to the Edinburgh Museum of Science andArt, I am now in a position to
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