I\liyiiili(ipi>i\i, Kiir^. .1 .W'ii' S f'cc us. -Li re i^cr. 2i)i.j 
Rhyiicliol^ora bccclwri, sp. nov. 
Fig. 4, brachial view. fig. 5, pedicle view, fig. (). anterior view. A 
typical example of the specie.'^. 
Fig. 7. brachial view, fig. 8, pedicle view. fig. 9, posterior view. 
Internal cast from the chert, .showing structnral features. 
Rliyiiclu'l'oni fiishilcsa (White). 
Fig. 10, i)edic]e view, fig. 11, lateral view, fig. 12, anterior view. 
.After Weller, for comparison. 
Shell Structure: I'udvr ;i lens of nKKlcratc ]:)()\v(.t tlic in- 
ternal lair.iiKC arc shown to he liit;hl\- ])unctatc while the super- 
ficial layer is inijninctate and ai)parently tihrous. Internal casts 
frtmi the chert heds j)resent a (lensel\- ])a])illosc appearance. 
Mcasurciucuts: .Avcrai^e diniensions of fifteen mature ex- 
amples from our collection give the following-, — Length, 
\2 mm.: breadth. 15 mm.; thickness. 10 mm.; width of sinus, 
at front. 8 mm. ; width of plications, o.() mm. 
Geological position : Upper Burlington limestone, from the white 
crystalline stratum and intercalary masses of chert, in association with — 
Atliyris incrassata Hall. Froductiis sciitircticttlatiis Martin. 
Athyris lamcllosa L'Eveille. Rctictilaria lincatoidcs Swallow. 
Camarophoria ringcns Swallow. Rliipidomclla burlingtoncnsis Hall. 
Cyrtiiia burlingtoncnsis Rowley. Rliipidomclla thicmii White. 
Derbyia kcokuk Hall. Schizophoria sivallovi Hall. 
Nuclcospira obcsa Rowley. Scminula ainbigua Phillips. 
Productus altcrnafiis Norwood and Spirifcr forbcsi Hall. 
Prat ten. Spirifcr logani Hall. 
Productus burli>tgfonciisis Hall. Spirifcr rostcllatus Hall. 
Productus Cora d'Orbigny. Syringotliyrisf plcnus Hall. 
Productus punctatus Martin. 
Locality: Three miles east of Fulton, Missouri. Greger collection 
number q8.^. 
Our collection contains specimens of this shell on which the plica- 
tions are but feebly developed on the anterior margin with the length 
and breadth equal and not exceeding 6 mm. This species is dedicated 
to the late Dr. C. E. Beecher of Yale University. 
Rhynchopora illinoisensis (Worthen.) 
The original description of Prof. W'orthen's species is here 
reproduced with some slight amendatory remarks. 
"Shell of about mediiun size, transversely ovate to sub- 
circular, wider than long, front nearly straight in the middle, 
beaks obtusely pointed. X'entral (Pedicle) valve slightly ele- 
vated near the beak and depressed towards the front into a 
