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APPENDIX.

contour of which it harmonizes best, if we might venture to assume that the two portionshave been incorrectly represented in the drawing.

Calymene variolaris, Brongn . Crust, foss. 14.3, PL I, Fig. 3, a, c, Parkins. Organ, rem. iii,PI. XVII, Fig. 16. Dalm .Balcead. 61. 1. Buckl. Bridy. Tr. Pl.XLYI, Fig. 6. Munster,Beitr. iii, 34. 1, Table Y, Fig. 1. Murchis. Sit. System, 655, Plate XIV, Fig. 1. MilneEdw. Or. iii, 326. Trilob. variolar. Schloth. Nachtr. ii, 34. 3. Bhacops variol. Emmr.Dissert. 20. 4. This species has already been mentioned (see ante, p. 83) as a form withwhich I am unacquainted. It has a semicircular cephalic shield with a very convexglabella which is undivided and broader at the anterior part, and with terminating angleswhich are suddenly produced into long points. The eyes are situated in the centre beside theglabella, on the surface of the cheek-shields, nearly as in Calymene Blmnenbachii, presentingalso the form of the latter. The body becomes more narrow towards the posterior part, andhas distinctly thirteen rings in Murchison’s figure, but only eleven in Brongniart ’s. Thecaudal axis, according to the reckoning of the latter, consists of twelve rings, and there arenine lateral ribs on the shield ; in Murchison’s figure I can only count seven lateral ribs, andfrom eight to nine joints in the axis. In addition to this, the whole upper surface of thebody is covered with large, strong protuberances, which are almost entirely wanting on thebody in Murchison’s figure, but are represented in several rows upon the caudal axis, whilstBrongniart ’s figure also shows strong protuberances on the body, and only one central rowon the caudal axis. Buckland’s figure agrees with Brongniart ’s, and is probably copiedfrom it. The species is found in the middle Silurian rocks of England, and also in theFichtelgebirge , on the authority of Count v. Munster. The Count’s figure agrees better withMurchison’s than with Brongniart ’s; the long pointed angles of the cephalic shield arewanting in it, as in the one figured in the Silurian System.*

Judging from these statements, I am almost inclined to consider the different forms asbeing specifically different, and to call Murchison’s species a true Calymene, Brongniart ’sand Parkinson’s a Bhacops. Boeck’s assertion, however, that Calymene variolaris forms adistinct genus, to which the Cal. punctata, Auct. also belongs, is opposed to this assumption.(See Keilhaus, Gaea Now. I. Trilob. No. 13.) The following authors treat of the last-named species.

Tril. punctatus, Brijnn, Kjobenh. SellsJc. Skrivt. nye. Sami , i, 394. 5. Schloth. Nachtr.ii, 37. 23. Entomostr. punct. Wahlenb. N. A. Ups. viii, 32. 7. Linn/EUS, Act. Bey. ac. Holm.1759. 22. 24, Table I, Fig. 2. Lehmann, Nov. Comm. Betropol. x, Table XII, Fig. 10.Beckm. Nov. Comm. Gothiny. iii, 102. Wilck, Strals. Mayaz. iv, St. Table III, Fig. 12.Calym. punct. Brongn . Cr.foss. 36. DhiM-.Balaead. 64.12. Murchis. 1. c. ii, 661, PI. XXIII.Fig. 8. Milne Edw. Cr. iii, 327.

All of them merely describe caudal shields, with the exception of Walilenberg, whoalso figures the central piece of the cephalic shield, which bears distinct marks of being aCalymene, especially in the thickened anterior margin of the head, and a peculiar structureof the lobes of the glabella, which reminds us of Cal. Blmnenbachii. But I doubt whether

* Cal. intermedia, Munster (35. 2, Table V, Fig. 2), is said to have four sulcations on each sideof the glabella, but resembles C. variolaris so perfectly in other respects, that I must yet doubt whetherit forms a distinct species.