New Species of Trilobitez, 375 



Ill^nus Milleri. (N. s.) 



Fig. 10. 



Fig. 10. — Illmnus Milleri. In this figure the head is drawn as if partly- 

 flattened out, in order to shew the cheek pieces. The 

 specimen is rolled up. In the natural position the pos- 

 terior margins of tbe cheek pieces are in contact with the 

 pleurae. The head and pygidiam are a little foreshortened- 



Description. Oblong oval, indistinctly trilobed, length one or 

 two inches, width variable, about two-thirds the length, propor- 

 tional length of head thorax and pygidium about as 6, 4£, 5^. 



Head transversely sernioval, evenly convex somewhat abruptly 

 elevated in the front half and more depressed behind, not trilobed, 

 genal angles rounded, eyes moderately large, lunate, less than 

 half their length from the posterior borders, about their own 

 length from the genal angle, and full six eights the entire width 

 of the head from each other. Cheeks rather small, fac'al suture 

 cutting the front margin a little within the parallel of the eye and 

 the posterior margin just behind the outside of the eye. The 

 dor.-al furrows are represented by two obscure not always visible 

 indentations each about one lire in width, situated at about one 

 fourth the length of the head from the posterior margin with a 

 distance between them about equal to half the distance between 

 the eyes. These pits are visible on the cast of the interior of the 

 head and constitute a ffood character for distinofuishino- it from 

 other species. 



Thorax of nine segments; the dorsal furrows represented by 

 two scarcely perceivable longitudinal depressions outside of which 

 the pleurae bend a little backwards. In well preserved specimens 

 which have not been distorted the line along the bend of the 

 pleurae is a well defined rounded angular ridge the distance 

 between the two lines bein-* a little less than twice the length of 

 the thoiax. 



Pygidium a little longer than the thorax, transversely broad 

 oval, depressed convex iu ihe fiont } bird, rather abruptly convex 



