170 CALIFORNIA ACADEMY OF SCIENCES. 



(referred by Dr. D. D. Owen, in 1852, to Illcenus ovalis); pi. 17, fig. 9, 

 Thaleops ? : pi. 18, fig. 2, Asaphus; fig. 10 (Asaphus platycephalus Stokes); 

 fig. 11, Ceraurus. 



- Report of a geological reconnoissance of the 

 Chippewa Land District of Wisconsin and incidentally 

 of a portion of the Kickapoo country, and a part of Iowa 

 and of the Minnesota Territory, etc. Washington, 1848. 



This report contains figures of the following fossils, which were after- 

 wards described by Dr. Owen under the names of Dikelocephalus minne- 

 sotensis, pi. 7, figs. 2, 3; Lonchocephalus hamulus, pi. 7, fig. 5; Dikeloceph- 

 ? iowensis, pi. 7, fig. 1. 



- Report of a geological survey of Wisconsin, 

 Iowa and Minnesota, and incidentally a portion of Ne- 

 braska Territory. Philadelphia, 1852, 638 pp., 27 pis., 

 16 sections and maps. 



Dr. Owen described four new genera of trilobites under the names of 

 Dikelocephalus, Lonchocephalus, Crepicephalus and Menocephalus. The 

 second genus is now classed as a synonym to Anomocare, with Anomocarc 

 chippewaensis and A. hamulus described in the report. There is a third 

 species mentioned by Owen on p. 624, and also pi. la, fig. 15. Pygidium 

 of Lonchocephalus ?, with long, slender, divergent caudal spines; also a 

 similar pygidium, figured pi. la, fig. 13, as Dikelocephalus ? iowensis. 

 Walcott, Bull. U. S. Geol. Sur., No. 10, p. 36, places the latter species 

 under a subgenus to Ptychoparia, using Dr. Owen's Crepicephalus for it, 

 on account of the peculiar pygidium, overlooking, however, the fact that 

 Owen has referred a similar pygidium directly to his genus Lonchoceph- 

 alus on p. 624 of his report. Under the law of priority the genus Ptycho- 

 paria replaces Crepicephalus, and the latter name should be cancelled 

 in toto, and not be retained in a modified sense. Lonchocephalus forms an 

 exception to this rule, if we divide the genus into two sections, retaining 

 Anomocare for the two species described by Owen, and Lonchocephalus, in. 

 a restricted sense, for "the pygidium with long, slender, divergent caudal 

 spines," including the Dikelocephalus ? iowensis Owen. 



The author also describes and illustrates the following species: 1, Dikel- 

 ocephalus minnesotensis n. sp. 2, D. minisccensis n. sp. 3, D. pepinensis 

 n. sp. 4, D. ? iowensis n. sp. 5, D. (jranulosus n. sp. 6, Lonchocephalus 

 chippewaensis n. sp. 7, L. hamulus n. sp. 8, L. sp.? 9, Menocephalus 

 minnesotensis n. sp. 10, Crepicephalus minisccensis n. sp. 11, C. ivisconensis 

 n. sp. 



The following species are mentioned or illustrated: 12, Phillipsia sp. 

 undet. I3 r P. granulifera ? 14, P. pustulata. 15, Calymene senaria 

 Conrad, pi. 2a, fig. 12. 16, C. crassimarginata, pi. 3a, fig. 6. 17, C. n. sp., 



