BRACHIOPODA. 875 
Oraniella ulrichl.] 
Craniella? ulrichi Hall. 
PLATE XXIX, FIGS. 38 and 39. 
1892, July. Craniella ulrichi HA1.T.. Palaeontology of Now York, vol. viii, pt. i, pp- I^'A 181, 
pi. ivll, flg.s. 1, 2. 
Compare Crania halli Sardeson.* Bulletin of the Minnesota Academy of Natural Sciences, vol. ill, 
p. 328, pi. IV, figs. 8-10; April, 1892. 
Description: " Shell moderately large. Outline normally circular. Apices .sub- 
central, slightly posterior, inclined backwards. Upper valve with the posterior scars 
large and the adjustors well defined; anterior scars subdivided, the outer or posterior 
portion possibly representing the insertion of the brachial muscles. The vascular 
sinuses make a 3-shaped curve on the lateral portion of the valve, with the crest of 
the double arch towards the center; narrowing rapidly, becoming indistinct over the 
anterior region. Lower valve regularly curved, evidently unattached at maturity. 
Anterior adductors very large, situated on a thickened posterior area. Posterior 
adductor and adjustor scars very faint, lying just within the margin. The vascular 
sinuses are a series of low grooves extending forward in subparallel lines from the 
anterior and lateral margins of the central muscular area. External surface of the 
valves smooth or covered with concentric sublamellose growth-lines. Length of an 
upper valve, 16 mm." (Hall, op. cit.) 
The specimens which can be referred to this species are free, separated, strongly 
convex valves, and are usually overgrown by bryozoans. Associated with them are 
numerous dorsal valves of Crania setigera Hall, also usually occurring as free valves. 
These can be separated from Craniella ? ulrichi, when the interior is not shown, only 
by their outer spinose surface. 
The material of C. ulrichi examined by Prof. Hall is identical with that which 
we have. All of the attached specimens on which he bases the statement, (p. 153) 
"is sometimes attached," have proved to be Crania setigera. Among the many 
specimens of Crania and Craniella observed in Minnesota, not a single attached 
ventral valve with the dorsal valve removed has been found. When the ventral 
valve is present it is attached to some other brachiopod and has the dorsal valve 
covering it. Such specimens have invariably proved to be Crania setigera. That we 
have both valves among the large and free specimens of Craniella ? ulrichi is prob- 
able, since the muscular scars and vascular markings are quite different in the two 
type specimens described and illustrated by professor Hall. This species is, there- 
fore, biconvex and probably attached by the apical portion of the ventral valve. 
Formation and locality.— Rare in the Trenton shales at Minneapolis, St. Paul and near Fountain, 
in the Galena shales, six miles south of Cannon Falls, Minnesota. 
Collector.i.—'E. O. Ulrich, W. H. Scofleld and C. Schuchert. 
Uus. Reg. No9. 7698-7700. 
*Mr. Sardeson's name may really apply to tliis species, but neither liis description nor figures are sufficiently diasinostlc 
to enable us to determine this point satisfactorily. On tlie otlier hand, it would seem that liis specimens must be distinct, 
because ho liad on several occasions been informed by one of us that Prof. Hall liad named and described the present species 
In the work above cited. As is well known, part i of that vohuuo was printed nearly two years before it was published. 
