58 SYSTEMATIC ARRANGEMENT 



2. Asaphus seticornis (Hisinger, Leth. Suec, second supplement, Tab. XXXVII, Fig. 2) cannot 

 be identified with T. fimbriatus, as figured by Portlock (/. c. 263, PI. I, B, Fig. 8), and Loven( /. c. 

 107, Tab. II, Fig. 1) ; but is a different and liighly characteristic species allied by its rounded caudal 

 shield more nearly to T. gramdatus than T. fimbriatus. A. cyllarus (Hisinger, /. c. Fig. 3) is, according 

 to Loveu, the same species, the spine of its cephalic shield being broken off. 



4. T. ornatiis : Limbo seuti cephalici antice angusto, estus posticeque lato, sed constricto ; anguhs 

 posticis acimiinatis, longe spinosis. 



Tril. oniatus, Sternb. Ver/t. 1833. 53. Fig. 2, a. Trin. radiatus, Murch. /. c. Fig. 3. 

 Emmr. Diss. 52. 8. Milne Edw. /. c. 3, and 332. Boeck, Gaca Norw. 42. 



Cephalic shield as short and broad as in the preceding species, but the border at the 

 anterFor margin smaller, and the tubercles not radiated, but in (four to five) concentric rows ; 

 the sides very much enlarged, with five to six rows of pores, but very much contracted again 

 towards the posterior angle, so that this region of the margin assumes the form of the letter 

 S. The terminal spine is long, slender, and pointed. The glabella is oval, higher, more 

 obtuse at the anterior part, and more globose. We are not yet accurately acquainted with 

 the rings of the body and tail. 



Remurk. — The statement in Murchison's work, that the enlarged margin in this species has 

 only two rows of tubercles, I must consider incorrect ; Count Sternberg describes from four to five. 

 Trin. asaphoides (Murch. /. c. Fig. 6) is probably a specimen of T. ornatus, in which the margin of the 

 cephalic shield is broken away. If this conjecture be correct, the caudal shield would be more shortly 

 triangulai', but the axis would likewise be many-jointed, having perhaps from ten to eleven lateral ribs. 

 Possibly, however, the body thus referred to may be referable to the species last described. 



N.B. Both the former species and the present occur, but rarely, at Builth in the 

 Llandcilo flags, and in Bohemia. Count Sternberg's specimens were found in a rock very 

 much loaded with pyrites, in the district between Zebrak and Proskales, in Bohemia. 

 Similar fragments have been found in the calcareous conglomerates of Carlshütten and 

 Beraun. These have been figured by Zenker, (Beitr. Table IV, Fig. N, 5) ; and partly from 

 these, partly from the caudal shields of quite a different species, the author has composed 

 his Otarion deffractum. This genus Otario/i must be banished from the list of Trilobites. 



5. T. tessellatus : Limbo seuti cephalici parabolico, tesselato-punctato ; scuto caudre triangulari. 

 Long. }^". 



Cnjptol. tesseU. Green, Mon. 73, Fig. 4 ; and Model, No. 28. Bronn, Lefli. i, 117, 105, 

 Table IX, Fig. 13. Emmr. Bisserf. 50. 2. Harlan, Zool. Res. 304. 



To judge from the impression, and from plaster casts, this species is more oblong and 

 smaller than the others ; the form of the cephalic shield more parabolic, the lateral lobes 

 of the rings of the body more arched, the caudal shield trilateral, rather acuminate. 



Occurs .in a black limestone of Trentonfalls and Glenfalls in New York ; also on the 

 Island of Montreal. 



Remark. — Neither representation nor description indicate any more definite differences, and I 

 therefore consider the species as uncertain. The same may be said with still greater reason of 

 T. Bigsbyi (Geology of the Island of Montreal, in Lye. of Nat. Hist, of New York, p. 214; and 

 Green, /. c.) and Nidtainia concentricu Eaton, (Geolog. Text -Book), both of which I consequently 

 jiass over. 



