200 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



Crepiccphalus Hall and Whitfield, 1877, U. S. Geol. Expl. 40th Pari., 

 Vol. 4, p. 209. (Discuss Crepiccphalus as a possible synonym of 

 Loganellus Devine, and refer a new species of Ptychoparia named 

 haguei to Crepiccphalus (Loganellus), also the new species nitidus, 

 granulosus, maculosus, unisulcatus, simulator, anytus, and angulatus, 

 none of which belong to Crepiccphalus.) 

 Crepiccphalus Walcott, 1884, Bull. U. S. Geol. Surv., No. 10, p. 35. (Calls 

 attention to placing of species referred to Crepiccphalus (Loganellus) 

 by Hall and Whitfield under Ptychoparia and remarks on Crepiccpha- 

 lus.) 

 Crepiccphalus Walcott, 1886, Idem, No. 30, p. 206. (Quotes Owen's 

 description and remarks, and concludes that Dikelocephalus ? iowensis 

 should be taken as the genotype.) 

 Crepiccphalus Owen, Miller, 1889, North Amer. Geol. and Pal., p. 540. 

 (Gives a generic description and refers to C. iowensis Owen as the 

 type of the genus, also includes many species of other genera under 

 Crcpicephalus.) 

 Crepiccphalus Vogdes, 1890, Bull. U. S. Geol. Surv., No. 63, p. 105. (Con- 

 cludes that Owen described a true Ptychoparia and not a new generic 

 form.) 

 Crepiccphalus Vogdes, 1893, Cal. Acad. Sci., Occ. Pap., Vol. 4, p. 293. 



(Reprint of comments of 1890.) 

 Crepiccphalus Walcott, 1899, Monogr. U. S. Geol. Surv., Vol. 32, Pt. 2, 

 p. 459. (Gives reasons for using C. iowensis as the type of the genus, 

 and illustrates an entire dorsal shield of an allied species, C. texanus 

 (pi. 55, fig. S)-) 

 Crepiccphalus Owen, Grabau and Shimer, 1910, North American Index 



Fossils, Vol. 2, p. 283. (Brief diagnosis of genus.) 

 The cephala of the species referred to Crepicephalits vary in 

 details, but all have the elongate glabella with sides converging 

 towards the front, and two or three pairs of more or less distinctly 

 defined short glabella furrows ; the occipital ring may have a strong 

 median spine, C. tripunctatiis magnispinus, or a minute node at its 

 center, C. iowensis. The frontal limb may be short and convex, 

 C. iowensis, or broad and depressed, C. texanus; the frontal furrow 

 may be narrow and simple, C. iowensis, or broad and marked by 

 three relatively large pits ; the frontal border may be narrow and 

 wire-like, C. iowensis, or broad and flattened, C. te.vanus. In all 

 species the eyes are of medium size, centrally placed, and with a 

 narrow ridge crossing the fixed cheek from the palpebral lobe to the 

 dorsal furrow near the anterior end of the glabella. 



The free cheeks all have a rather strong genal spine. The course 

 of the facial suture is similar to that of Ptychoparia. 



The thorax has from 12 to 14 transverse segments ; pleural 

 furrows well defined, and termination of pleural lobes of each seg- 

 ment slightly falcate. 



