<!'<>1>A 



: 



HECTION. 



utatttiMi Kim. i*jr. ultlata U . & S. Stone's Hirer group. 



uitl HU.-k Kiv. grs. B. , k 8. fill .up. 



(Wptfoa IT. \ S. Trent. m gnmp. 



:.et Hlv.AWkRT.gr>. Awtortaeta Hall. Trenton group 

 f B. jwMt0vn EmnioDS. Trenton group. 

 Foreign species. B. (wdfeanomUi Schmidt, Lower Silurian, Russia. 



B. NASIIVII.I.KNSIB SECTION. 



MuAwVkiifM Ulni-h. Trenton group. /' fxracuta Ulrl.-li. Trrnton group. 



mibfeyiS.. B. linyularit Ulrlch. Trenton group. 



ririch. Tr.-ntoiiKroup. 



rirh. Trvnt..n group. B. nana, var. fubpatuln I'lrlch. Tr.-nlon group. 



.irrontnwi Ulrlch. Trenton group. B. rimulatrix Ulrlch. Richmond group. 



numi I'lrlch. Un-aliKiiiil 



M K. l{x)mer. (Leth. Geognostica, 1876.) Shell symmetrically coiled 

 in <>!! plane; volutions numerous, enlarging gradually, scarcely embracing, the 

 )>eing a large open umbilicus. Aperture abruptly expanded at maturity, 

 tnnniK't like; peristome thin, the outer portion slightly sinuate. Inner volutitm- 

 with a slit band as in lin<;ini<i. This is replaced in the outer half of the last whorl 

 by a long narrow opening or slit which, however, does not extend to the apertural 

 expansion, luit is closed some distance behind it. Surface marked with simple or 

 suhlauiellose lines of growth and more or less oblique, irregular and sometimes 

 interrupted or wavy revolving lines. Type, S. megalostoma Eichwald sp. 



AMERICAN srr.cm. 



8. tntelli Whit Hold sp. Stone* River gn>u|>. 8. imbricatn U. & S. Richmond group. 



S. biK/Ji, rar. Jvntudbouu Ulr. Black Rlv. group. S. rirhmondentit Ulr. Richmond group. 



S. crpaiuo Hall sp. Trenton group. S. caiMdenfi* Billings. Hudson River group. 



H tculptilit U. & S. Trenton group. S. /ralernuj Billings. Hudson River group. 



:OI'EAN SPECIES. 



& meyalottama Eichwald. Lower Silurian. 8. locator Eichwald Bp. Lower Silurian. 



8. comprtua Eichwald sp. 



. Hall.* In all respects like Salpingostoma excepting that an 

 expanded aperture is developed at frequent and regular intervals, and the dorsal 

 slit closed at corresponding periods, so that, instead of a continuous long opening, 

 there is a series of small, elongate elliptical perforations. Type, T. alpheus Hall. 



AMERICAN SPECIES. 



/AftuHall. Niagara group. T. triytmottoma Hall& Whltfleld. Niagara group. 



T. eMco0MMit McCheaney sp. Niagara gr> T. anguttata Hall sp. Niagara. 



7'. pro/undu Conrad sp. Lower Helderberg group. 



T. lonyihuUnaki Llndstnmi. Up. Sllur., Gotland. T. eomprettut Llndstnim. Up. Sllur., Gotlaml. 

 T. mmdeni Kth.-riilge. Jr. ?TrlaMlc, New Smth Wales. 



CONRADKI.LA. n. gen. (Vhr'njmolittjt, Conrad, 1838, Ann. Geol. Rep. New York. 

 p. ll'.i.i Shell coiled symmetrically, general form as in Cyrtolites and Oxydiscus, the 

 volutions enlarging gradually and being strongly keeled dorsally. Aperture oval or 



Tweotl.U, Rp. S.- York St. Mu. Nt. Ill.t . p. MT; IS*. 



