BRACHIOPODA. 373 
Crania granulosa.] 
the Trenton shales often attain a greater size, and have the sette usually less pro- 
nounced, while the beak is obtuse, the outline variable, and the cardinal margin 
only in rare instances straight. Free dorsal or upper valves are common, and but 
few specimens have been secured in which the valves conjoin, and are attached to 
an Orthis or Ra/inesquina. These attached specimens are marked more or less with 
their host, causing the characteristic surface pustules to become obsolete, while 
the stricE of those growing upon smooth surfaces have developed the seta3. In 
specimens where these pustules have been removed by weathering or other causes, 
it is very difficult to decide whether they are individuals of C. setigera or C. trenton- 
ensis. Such specimens are usually referred to the latter species, but they commonly 
preserve a few pustules near the margin. 
A specimen of MonticuUpora, with an individual of this species* attached, also 
has a parasitic species of bryozoan growing on it, which grew towards the Crania. 
Its growth, however, was limited towards the anterior portion of the Crania, leaving 
between it and the encroaching bryozoan a space 3-4 mm. in width. This limiting 
of the growth of the bryozoan may have been caused by the frequent extension of 
the arms of the Crania during life. 
Formation and locality. — In the Trenton limestone at Minneapolis; Trenton shales at Minneapolis, 
St. Paul, Cannon Falls, Fountain, Chatfleld and Preston, Minnesota. Also from the Trenton at Decorah, 
Iowa; Mineral Point and Beloit, Wisconsin. In the Salmon River group or Loraine shales at Wilmington, 
Illinois. 
Collectors.— C. L. Herrick, W. H. Scofleld and the writers. 
Mus. Reg. Nos. 718, 5500, 7692-7696, 7958, 
Crania granulosa iV. H. Winchell. 
PLATE XXIX. FIGS. 34 and 35, 
1880. Crania granulosa N. H. Winchell. Eighth Annual Rep. Geol. and Nat. Hist. Survey of 
Minnesota, p. 63. 
Original description: "Shell small, but prominently elevated at the beak; orbi- 
cular or somewhat widened between the antero-lateral margins; no concentric stria" 
or undulations visible on the exterior of the shell, nor radiations; the whole surface 
of the dorsal valve uniformly fine-granulated or pustulose; these granulations not 
disposed in any apparent order. The lower valve unknown."' 
Crania scabiosa Hall, when growing on a bryozoan, usually has the upper valve 
strongly pitted. Specimens of this nature have received the name C. muUipiindata 
Miller and Dyer. The outer surface of C. granulosa, however, is not pitted, but is 
crowded with small pustules irregularly arranged. 
Formation and ZocaZiYj/.— Trenton limestone at Minneapolis, Minnesota. 
Mus. Reg. No. 708. 
♦This spocinion is figured in Pal.-N. Y., vol. vili. pi. ivH. fis. 14, 1802. 
