BlUTISH FOSSILS. 



Decade XI. Plate VI. 



SALTEEIA PRIMiEVA. 



[Genus SALTERIA. Wtv. Tiiomso^^. (Sub-kingdom Articulata. Class Crustacea. 

 Order Trilobita. Family Trinucleidsc.) Body oval, tapering backwards. Head large, 

 semi-lunar, margin very narrow, simple, surrounding a broad limb. Glabella inflated, 

 furrowed. Facial suture following the edge, except through a small portion on 

 either side, where it becomes nearly vertical and slightly emarginates the upper surface, 

 cutting off a narrow free cheek. [Eyes minute, linear.] Thorax of few segments. 

 Tail of many segments.] 



Diagnosis. >S'. fere uncialis, lata, ovata. Caput semilunare Umbo 

 angusto brevi convexo marginato ; glabella ovata pyriformi depressa, 

 genis multo majori, utrinque puteis tribus brevibus notata ; sutura facialis 

 sub fronte ambitui parallela, dein per quartam partem extcrnam limhi 

 conspicua subverticalis. Thorax articulis truncatis. Cauda triangidaris 

 multisegmentata . 



We have no hesitation in placing Salteria among the Trinu- 

 cleidce. It is evidently closely allied to Dionide, especially to 

 Angelin's species D. euglypta. They have nearly the same form 

 of glabella with longitudinal grooves ; the same narrow, smooth, 

 concave limb; the same structure of body rings and tail. The great 

 difference between them consists in the presence in Salteria of a 

 distinct though linear free cheek, and apparently of a true eye in 

 its normal position. In these characters our fossil at once recalls 

 Cyphoniscus, placed by Mr. Salter, apparently with much reason, 

 among the Olenidce. It also resembles this genus in the peculiar 

 character of a delicate striation on the cast of one portion of the 

 head, while the remainder is smooth. We have a specimen of 

 Cyphoniscus from the same beds in Ayrshire retaining the free 

 cheek, and showing a well marked narrow rim, ending in a long, 

 straight, genal spine. The specimen is unfortunately too imperfect 

 to show the eye. In Cyphoniscus the structure of the body rings 

 is quite characteristic, and the small Glenoid tail is very different 

 from the compound tail of Salteria. 



[xi. vi.] 11 F 



