104 SYSTEMATIC ARRANGEMENT 



Gaea Norw. i, 34. Emmr. Diss. 34. 17. Pander, Bcitr. 137, Tab. V. Figs. 

 9, 10. L. V. Buch, Beitr. 43. Triloh. Esmurkii, Schloth. Ms, 1826, 315, 

 Tab. I, Fig. 8. 

 Crjjpionymus Biidnljj]iü,^\cw.'W. Observ. etc. 50. ^ 56, Tab. II, Fig. 1, a, h. Cr. Mosenhergii, 

 ibid. 48, Tab. Ill, Fig. 3, a, b. Or. Parkimonii, ibid. 51. ^ 57, Tab. IV, Fig. \,a,b. 

 Cr. Wahlenhergii, ibid. 50, Fig. 3, a, b. 

 Isotdes crassicauda, Milne Edw. Cr. iii, 300. 6. 

 The following seem to be young individuals of the same species. 

 Elanus perovali.'i, MuRCHis, Sil. Syst, iii, 661. PL XXIII, Fig. 7. 



Localiti/. — Occurs in the transition limestone of Sweden ; at Husbyfjol, in East Gothland ; 

 at Osraundsberg, in Dalecarlia ; in Esthonia, at Revel, and at St. Petersburgh ; in England, 

 in the Caradoc sandstones of Shropshire and Montgomeryshire. 



This common Trilobite is easily to be recognized by its peculiar habit, and is distin- 

 guished from the following species by the eyes, which are situated far towards the posterior 

 part, close to the borders of the head. 



2. ///. giganteus : Oculis in medio latere scuti cephalici. Long. 3-6". Tab. Ill, Fig. 10. 

 GUETTARD, Mem. do TAcad. Boy. etc. 1757, torn, xv. Tab. VII, Fig. 2 ; Tab. VIII, Fig. \; 



Tab. IX, Fig. 1. 

 Occurs in the clayslate of Angers ; according to a specimen in the academical 

 collection at Halle. This species seems rare, and not to have been found by any observer 

 since Guettard's time ; it is, however, as distinct as any other species of Trilobite. The 

 splendid specimen in the collection above named, of which I give an accurate figure, shows 

 only the cast of the animal ; but exhibits all the characteristics of Ulanus, together witli 

 the peculiarity which mai'ks it as a distinct species : this is seen in the position of tlie eyes, and 

 is very manifest. The covering plate at each side of the cephalic shield is, however, only 

 visible on the latter, the maxillary shield and the eye itself are wanting ; I have endeavoured 

 to indicate its position by a dotted line. 



Division B. — The axis of the body comparatively broader, and only imperfectly sepa- 

 rated from the lateral lobes by a slight longitudinal sulcation. — Bumastes, Murch. 



3. IJl. (Bit.) burrieims ; Oculis margini postico scuti cephalici approximatis. Long. 2-3". 

 MuRCH. Sil. System, ii, 656, PI. VII, Fig. 3, «, b, c, PI. XIV, Fig. 7. Jukes and 



Sowerby, Zoitd. May. of Mit. History, ii, 41. Silliman, ^'/ww. Journ. of Science, 

 1832, vol. xxiii, I. p. 203. Emmr. Dissert. 33. Milne Edw. Cr. iii, 295. 

 Locality — The middle Silurian strata of England, at Barr, in Staffordshire, at Brandlodge, 

 and Presteign. This Trilobite resembles so much the ///. crassicauda, with the exception of 

 the body, the broad axis of which is not strictly separated from the lateral lobes, that I 

 hesitated for some time before I could decide upon its being a different species. Isolated 

 cephalic and caudal shields can scarcely be distinguished from the former. 



Remar/c. — Nilens glomerinus, Dalm. [Arsberatt, 1828, p. 136 ; Hising. Letli Sitec. 16), seems to be 

 the same species. 



