DESCRIPTION OF GENERA AND SPECIES. 115 



across the lobe, leaving a short portion of the broad margin extending obliquely 

 forward and outward at the base of the postero-lateral spine; in front of the pal- 

 pebral lobe the facial suture extends forward and slightly outward to the front 

 margin. 



There are several specimens of a hypostoma associated with the species, that 

 appear to belong to it. The central portion is convex, subovate, and crossed toward 

 the front by a strong furrow subparallel to the rounded front margin ; a narrow rim 

 surrounds the front and expands into two ear-like, flattened projections opposite 

 the strong furrow crossing the central portion; the margin then contracts so as to 

 leave a narrow, rounded rim opposite the convex portion of the posterior part of 

 the central body; it then expands so as to form a subtriangular limb on each side 

 at the postero-lateral angles of the hypostoma. The hypostoma is of the same 

 type as that of Damcsclla blackwcldcri [plate 10, fig. iz']. 



The associated pygidium is transversely semicircular, with a spinose margin 

 and convex, conical axis; the axis is divided into five rings and a subtriangular 

 terminal portion by five transverse furrows ; the two anterior rings are rather convex, 

 while the three posterior are but slightly defined by shallow, narrow, transverse 

 furrows. The pleural lobes are slightly convex out to the geniculation, where the 

 slope is somewhat abruptly downward to the end of the falcate termination of the 

 segment outline on the lobe ; the furrows crossing the axis extend out on the pleural 

 lobes, so as to define a narrow anterior segment and four posterior segments and 

 a central portion extending down from the axis; each of the segments terminates 

 in a falcate, backward-curving, short, flat spine, of which there are six on each side, 

 one for each of the segments and two back of the axis ; there does not appear to be 

 any clear indication of a border, as the space is occupied entirely by the segments 

 and their falcate ends. 



The surface of the glabella, fixed cheeks, free cheeks, and occipital ring is 

 marked by numerous, rather closely set, depressed pustules, between and on which 

 there are very fine punctse, as determined by a strong lens. The surface of the 

 pygidium is marked by strong pustules or granules that are thickly set on the 

 segments but not on the furrows. There appears to be considerable difference in 

 the strength and size of the granules on different specimens. This may be simply 

 a matter of the state of preservation, or the amount of wear to which the crust has 

 been subjected, or it may indicate a variety or even a different species. 



A cephalon 3 mm. in length has a width of 5 mm. at the exterior of the pal- 

 pebral lobes, and a width at the base of the glabella of 2 mm. 



The pygidium illustrated by M. Bergeron as Dicellocephalus ? sinensis Bergeron 

 [1899, p. 508], which occurs at this same stratigraphic horizon in China, appears 

 to resemble more closely than any other form the pygidium of this species. As 

 illustrated and described by M. Bergeron, it differs from Stephanocare richthofeni 

 in its shorter axis, five instead of six spines on the margin, and a smooth instead 

 of a granulose surface. Stephanocare richthofeni has a cephalon of essentially the 

 same type as that of Damesella blackwelderi [p. 125], but the pygidium differs in hav- 

 ing its anchylosed segments extending out directly across the border into the falcate 

 spinose ends, instead of stopping within the border and having spines representing 

 the extension of the segments extending outward from the border. 



Specimens of Drepanura premesnili Bergeron [1899, P- 59] an d Agnostus 

 douvillei Bergeron [1899, p. 503] are associated with Stephanocare richthofeni; and 

 Liostracina krausei Monke, Teinistion lansi Monke, and Shantungia spinifera Wal- 

 cott [p. 148] occur at the same horizon and in many instances on the same hand 

 specimen with Stephanocare richthofeni. 



