162 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 

 CONOCEPHALITES lOWENSIS. 



PLATE YII, riGS. 29 - 33; AND PLATE VIII, FIGS. 10 - 12, & 30. 



Jjikcloccphalus iowensis : Owen, Geological Report of Wisconsin, Iowa and Minnesota, page 



675, Tab. I, f. 4, and Tab. I A, f. 13. 



Conocephalitcs iowensis : Siiumard, Trans. Acad. Sciences of St. Louis, Vol. ii, p. 104. 

 Dr. Shumard also gives the following synonymy : 



Crepicephalus : Owen, Ibid. Tab. I A, f. 10, 16 & 18. 

 Undet. Trilobite : Id. lb. Tab. I A, f. 11. 

 Lonchocephalus : Id. lb. Tab. I A, f. 15. 



The species is of medium or large size. Head depressed convex. 

 Glabella truncate conical, moderately convex, the centre some- 

 times more elevated and longitudinally subangular in the 

 middle, a little flattened on the sides, the length (excluding the 

 neck-segment) equal to the width at the base, truncate in front, 

 with the angles abruptly rounded : lateral furrows obscure, and 

 apparently not existing in younger specimens. Occipital furrow 

 linear, rather shallow in the middle, deeper and sharply im- 

 pressed towards the extremities. The occipital ring has the 

 same elevation and convexity as the base of the glabella, wider 

 in the middle, straight on the anterior edge, and converging on 

 the posterior margin from the middle to the extremities. Dorsal 

 furrows strongly but not abruptly impressed at the sides, and 

 at the anterior angles of the glabella : the groove in front of 

 the glabella is more shallow than at the sides. 



Fixed cheeks rising gently from the dorsal furrow, moderately 

 convex, not as high as the glabella. Posterior limb with a Avell 

 defined furrow : palpebral lobes long reniform, and "separated 

 from the cheeks by a strong sigmoid furrow." Frontal limb 

 about one-fifth of the entire length of the head ; "having a 

 deep transverse groove a little in advance of the middle," with 

 a strongly elevated and rounded or "cordlike" anterior margin. 



Movable cheeks comparatively small, narrow elongate, with a 

 thickened border which is prolonged into a slender spine. Eye 

 tubercle large. 



Thoracic articulations of moderate strength ; having a simple 

 groove wdiich becomes gradually narrower towards the outer 

 end, and dies out at the commencement of the recurving ex- 

 tremities. 



