8 NILS HJ. ODHNER 



different also. The median tooth shows indications of being 

 pectinated and in reality carries only slight traces of one denticle 

 on each side of the small median cusp (cf. Grieg, fig. 10, and 

 the present fig. 1), thus representing another type than T. plebeia 

 (cf.SARS 1878, pi. XV, fig. 1). The lateral teeth, outside the median 

 plate, are of about the same size as the following marginals, 

 and have a sharp crest which rises to a blunt hook situated 

 medially, whereas in T. plebeia this plate is larger than the 

 marginals, and is produced to an apex in the posterior inner 

 corner (cf. Bergh, 1. c, pl. L. figs. 21, 22). In the shape of the 

 lateral teeth, T. griegi more resembles T. hombergi (cf. 

 Bergh 1. c, pl. LXXII. fig. 13) or T. reticulata (the same plate, 

 fig. 23). 



Above all, however, the mandibulae prove that the present 

 form must be considered a distinct species. They are of a horny 

 brown colour, and their margins are very thick, dark-brown in 

 colour, and furnished with a single series of large denticles 

 extending all along the margin. The denticles are finer in the 

 upper (frontal) part, very coarse in the lower (hinder) part of 

 the mandibulae; in the median space they are replaced by low 

 undulations (about 6 in number). 



In the shape of the mandibula the present form approaches 

 T. hombergi more than T. plebeia, which, like T. lineata (cf. 

 Alder & Hancock) has a thin and smooth masticatory margin 

 of the mandibles; this margin is, however, bordered on the out- 

 side by a band of small papillae (cf. the figures by Alder &■ 

 Hancock and Bergh). In T. hombergi a similar zone is also 

 present (cf. Bergh), but the real masticatory margin itself is 

 serrated, but that only in its 'posterior half, and each loolh 

 consists of isolated crowded cones (Bergh pl. LXXII, fig. 6 a). 

 In T. griegi, on the contrary, the denticulation is, as named, 

 extended to the whole length of the margin, and the denticles 

 are simple, though they still show a slight striation as an indica- 

 tion of a composition like that of T. hombergi. 



