|ilr Vnoi<rill.ni t 



weaker and (ml u sharply defined as the m ir k -m.-.i ..ne. A I*, ml midway between the baod and Ibc suiun< 

 line* a small ridge or carlna divide* the upper |..pe Into iw<i flat <ir slight !> concave space*. Nearly the 

 ame distance beneath the lower margin >( the )>an>l In the typical form ! the specie* we meet with ti.< 

 Unit and lrunge*t of aU vlng rib*. Those rlb*,ex.-ejitmtf occasionally tho Drat, are wanting 



In a variety which, If It in desirable to name It, might he called \ir.obnoleta. Umbilicus exceed I only small, 

 sometimes closed by a slight overlap of the Inner Up. Aperture sulxjvaU-. rounded below, an<l : 

 .tr.iifc'h! ,ii in,' Inn- Lines of growth sharp, thread-like, regular, either floe and equal on all paru 



of a whorl <ir they may be farther apart with Interpolations on the upper slope u shown In fig*. M and M. 

 The lunulm of the band are fine and regularly curved. 



This species Is not closely related to any American fossil known to us. It resemble* l'Utho*pira 

 ttnitlr Hall sp. In Ite general form and sle and cast* of the Interior are not easily distinguished. They 

 ar.-, however, wi.i.-iy distinct genetically and as long a* good exteriors are available there Is little danger 

 of confusion between them. In the Pletkotpira the band Is simple and concave (not bl-concave) while the 

 very delicate line n.-.c : t>. - itur.- and the other on the lower half of the whorl compare very 111 with the 

 revolving ridges and rib* of Lopltotpira lirala. A true relative Is described by Llndstr.mi from the Upper 

 Silurian of Gothland as I'Uurotamaria rotasto. That It was derived from the same stock a* our specie* 

 seems ver for, aside fn>m several minor difference*, the same characters occur in both. L. lirala 



ha* a relatively higher spire while the central line of the band is not as prominent as In L. rolnuta. 



Our main reason for referring these two species to Lophotpim Instead of Setlya Is that the band U of 

 \ m-t.M'1 of the concave type. With L. humiUt L'lrlch as an Intermediate form It is not difficult 

 to recnm-ile the other characters with the more common type* of LopAotptro. 



and locality. Not uncommon, chiefly M cuts of the interior, In the Utlca group at 

 Cincinnati, Ohio. 



cwi*<m.-E. o. uinch. 



LOPHOSPIRA (?) KWOXVILLEN8I8, . Sp. (Ulrtcli.) 

 PLATE LXV. rtO8. 3S- 0. 



Eight 30 to 40 mm., width about the same; apical angle about 105; whorls throe and a half or four. 

 The shell Is about the Mze and looks much like Tmeh'memu btloitennx and T. eecentrica, the whorls having 

 a broad vertical peripheral space bordered above by the slit-hand and below by a simple angle, and the 

 aperture being oblique and sub*|uadrate or, If the small lower-outer side be considered, subpentagonal In 

 outline, with the low. T half of the entire perlstome thick and reflexed. The upper side of the whorls is 

 distinctly concave to the narrowly yet deeply Impressed suture. The channel-like character of the suture 

 Is discernible only In a view of the upper side. The basal slope to the edge of the moderate umbilicus Is 

 more or less flat t.-n.-l. The silt-band, which occupies the upper of the two peripheral angles, consist* of 

 a barp rldge-llke center with a delicate raised line on each side of its base. The surface markings consist 

 of lines of growth only. These curve very strongly backward and are comparatively weak on the concave 

 upper slope. Beneath the slit-band they Increase In strength downward, while their direction Is first, 

 with a moderate curve forward, down to the lower angle of the vertical periphery of the volution. Here 

 they turn backward and proceed across the base to the umbilicus In a direction conforming with the 

 broadly sinuate under lip. The depth of the sinus, however, seems to have increased with age. 



Though there may be some doubt as to the strict propriety of referring this and the two following 

 specie) to LopAofptro, we believe that a careful consideration of the whole of their characters will show 

 that of all the established genera the claims of the one In which we have placed them are supported by 

 the strongest evidence. We take It for granted that, despite their remarkable resemblance to the most 

 typical species of Trockonema and the remote genetic relations so strongly Indicated therein, all will agree 

 that th> possession of an unequivocal silt-band renders an alliance with Trnthonrma out of the question. 

 We say this too without losing sight of the fact that we describe specie* of that genus (e. g. T. ntrorw 

 and T. Ixllulti) having a oolrh In the aperf nearly the same character and at the same point at 



which It occurs In the trocbonemoid species of Lophotpira under consideration. There Is one 1< . 

 about the*.- notched Troctonenuu that must always distinguish them, the upper peripheral angle toward 



