GASTROPODA. 1015 



tnrm. 



l-r.ATK I.\\ I li. s. !-; m 



Hi* mm., apical angle very constantly about 18. Shell small, slender; volutions about 



fourteen In a length of 30 mm. : rounded, generally with a slight animation, on which lie* the band, a 



u-n.-ath th> middle; band seldom preserved, when perfect, rath.-r narrow, smooth, flat or faintly 

 concave ami margined on each aide by a delicate raised line; suture simple, deep; lines of growth One, 

 lM-ii'l Ing strongly backward from the -uturv t<> the band, and beneath this curving very strongly forward 

 again. th<> whole Indicating a deeply notched mouth ; aperture a little higher than wide, rounded except 

 below wb<-rc It Is somewhat |.r.lu.--,r. inn<>r lip reilected, forming a slightly twisted and thickened 

 colunu-lla. 



The original of fig. 22, which was found with many specimens like tigs. 20 and 21, In the Richmond 

 group ru-ar Spring Valley, ban the whorls too angular. Perhaps It would be better to place It with the 

 var. yoodkueiuii. 



Variety ANUTSTATA Hall. 

 PLAT! i.\\ nos. i 



Has more uniformly rounded whorls and slightly wider band tban the typical form. So far as 

 observed, this variety never reaches a length of 26 mm., the majority of specimens varying between 

 17 and 20 mm. 



Variety SUBLAXA, n. rar. 



ri.vn i.\\ i 

 Tin- form is distinguished )>y Its rather loosely coiled volutions, deep obll<iut> suture, and wideband. 



Variety MULCT VOLVIS, n tar. 



PLATE LXX, FIO8. M-K. 



nguished from the foregoing varieties by IU closely wound, vertically depressed volutions. 

 ? Variety OOODIIDKNBIS, n. var. 



PLATE LXX. PIGS. tt-O. 



In this form the whorls are unusually high and angular, almost rivalling, In the latter feature, the 

 -pecies, with which, moreover, It was found. Hut the apical angle Is only about 18 degree*, and this 

 agrees with //. yracilit, while It Is too narrow for 11. tubangulata. We have only two specimens and there- 

 for* d<> not like to say anything positive about the form. A larger supply of specimens may show It to be 

 net than It now appears. At any rate. It seem* worthy of recognition as a variety. On plate 

 I.\ \. flg. 22 gives a view of a similar specimen which occurred with H. yraeOu and the var. mxlticolns In 

 the i group at Spring Valley. Possibly this represents a later appearance of var. gootttutntit. 



v of //. i/r irs In greater or leaser abundance at most localities in the 



the eastern ha ite* and Canada exposing the rocks of the Trenton and Hudson River 



period*. Really satisfactory specr r, aiy rare, especially such as preserve th.- sh.-ll n 



face marking*. The var. nnytataln Is scare. .-uishable In the condition of casts of th.- int.Tlor, In 



which It Is usually found, from th- typical form of the species, but It Is probably safe to say that all the 

 specimens of the specie* found In .Toup belong to this variety, since none of th.- oth.-r 



varieties have so far been ldentm.fi in r.*-ks t,, .,. ,,. r Kr ,, u ,, , n yu*aia Mem* 



to occur as far down a* the Calclferous sandstone, since we can see no difference whatever between the 



H River form and Murrkinmia grotto** of \Vhitri. -1.1. Th- oth.-r .,. tm,.-s associated 



with the typical form of the species, but they are readily enough dl*t!uirulhh<-d, either as cut* or shells, 

 by the peculiarities above mentioned. 



