OF THE SPECIES. 017 



the body ; glabella almost twice as long as broad, anteriorly rather hemispherical, posteriorly 

 contracted, with the vestige of a knob at each side. Six distinct rings of the body, the 

 axis of each scarcely half as broad as the lobes. Caudal shield triangular, with a slightly 

 elevated angle at the exterior margin ; its axis only articulated to a little beyond the centre 

 with six rings, afterwards simple : the lateral lobes furnished with six radiating striae 

 divided towards the margin. 



Remark. — Described from specimcus ia the IMuseum at Halle, occurring in a yellowisli grau- 

 wacke. Found also in the lower Silurian strata of England, North America (Montreal), and Bohemia. 

 (Sternberg, Verhandl. d. vat. Mus. 1833, Fig. 2, b.) 



2. T. yranulatus : Limbo scuti cephalici orbicul.u'i, puuctato ; angulis posticis lobatoproductis, brc\ e 

 mucronatis ; scuto caudse subsemich'culato, rhachi tota annulata, annulis sex. Long. %". • 



Jief. — Ei/t. yranulatus, Wahl. «. acf. Ups. VIII, 30. 5, Table II, Fig. 4. Asaph, gran. 



Dalm. Pal. 43. 4, Table II, Fig. 6. Brogn. Cr. f. 36, PI. Ill, Fig. 7. Milne 



Edw. Cr. Ill, 332. Boeck. Gaea norm. 41. Trinudeus Lloydii, MuRCH. ^7. Syst. 



Pt. II, GGO, PI. XXIII, Fig. 4. Emmr. Biss. .53. 9. Milne Edw. /. c. 4. Loven, 



Ofcers K. V. A. Forhandl. 1845 ; 109, Tab. II, Fig. 2. 



Cephalic shield, like that of the preceding species, but the posterior angles produced 



into broad, parallel, punctated lobes, which project backwards beyond the rings of the body, 



and finally terminate in a delicate spine rather shorter than the lobe. Rings of the body 



not so narrow as in former species, and more than half as broad as the lateral lobes. 



Caudal shield, a segment of a circle smaller than a semicircle ; the axis indistinctly 



articulated ; the sides without ribs. 



Occurs in a black limestone belonging to the upper members of the lower Silurian 

 series in Great Britain and Scandinavia. 



3. T. fimbriatus : Limbo scuti cephalici dilatato, radiatim granulate ; angulis posticis irregulariter 

 granulatis, subrectis, mucronatis; cauda tota annulata, annulis 12-13, long. 1". 



Ä/.— MuRCH. /. c. PI. XXIII, Fig. 2. Luid. Ic////oj/r. p. 97, Tab. XXIII. Emmr. Diss. 



52. 7. Milne Edw. /. r. 2. Portlock, Bcporf, ^-c. ,- 264, PI. I, B, Figs. 11, 12. 



Sars, Isis, 1835; Tab. VIII, Fig. 4, d (certainly not the caudal shield of an 



Ai//pt/,r). 



Cephalic shield shorter and broader than in the preceding species ; the mai'gin furnished 



anteriorly and at the sides with radiating pores ; the posterior angles not contracted, 



irregularly granulated with pores, with a long, nearly straight, terminal spine. The 



glabella but little diminished posteriorly, with slight traces of lateral impressions, but 



little longer than broad. Rings of the body indistinct ; body shield oblong-triangular ; the 



whole axis articulated as far as the extremity, long, consisting of thirteen or more rings ; 



the sides with twelve radiating ribs ; the margin acutely angled. 



Remarks. — 1. T. nudiis^ CSlurch. I. c. Fig. 5) I am inclined to consider the same species, with 

 the margin broken off at the cephalic shield. See Emmerich, Fig. 5.* 



* Note, by the Editors. Trinudeus nudus is really a species of Amjryx, as may be seen by con- 

 sulting the original specimens in the Museum of the Geological Society of London, and stiU more 

 perfect ones in the collections of the Geological Survey of Great Britain. 



