GASTROPODA. 1019 



Ctalooulu* ) 



Concerning the i.I.-ntlty ,,f the species Jut described and Hall 1 * Jfm**oiUa major, we can only say 

 that after as careful an InvesUjjatlon as was possible without having an opportunity of studylnit the -Tin- 

 Inal type*, we arc fairly well satisfied that our shell* are really the same as the one flKured by Hall. 



his ordinal lot of specimen* lnclu<le<l other forma of these Urge hells, but If the present species la, 

 as we bellete, amon^ them, then It w..uld be well to retain the name major for It and throw out the 

 others. Thin course Is to be commended If only for the reason that It will greatly simplify matters In Hi-- 

 way of synonoray. 



>ften aaaerted that // major Is but a large frm of //. btUicincta, while Whiteaves would make 



It the same as Billings' 3f. UrrrttforJL II " r, and providing that we have correctly ldfiitlil.il these 



, the totally differ, nt suture of //. m<tfor shows conclusively that It Is not even closely related to 



..f th,. in., nth- r species mention 1 *!. 



The unusual character ..f the sutural region, which is well shown In our flg. 7, In of Itself sufficient 

 to distinguish this shell from all associated gastropods. CasU are separated from those ..f //. trtntonentit 

 \,y their narrower apical angle (taking the whole shell Into consideration), by the less uniform convexity 

 of the whorls, and the rectangular Instead of rounded junction of the upper and outer sides of the whorls. 

 The last difference is very striking when transverse section! of the whorls are compared. The lower 

 extremity of the mouth also Is much leas produced and therefore blunter. CasU of Lophtapira. augurifaa 

 Billings sp., arc sometimes found In the same layers with //. nuijor, but the wider apical angle and 

 obtusely anuulated whorls of the former rentiers confusion In this case highly Improbable. If perfect 

 shells of these various species could be compared, we are convinced that the merest tyro In the science 

 would separate them at once. 



Forma/ion and locality. Though widely distributed, this species appears not to be abundant at any 

 locality. It Is restricted to the Trenton group, and In Minnesota occurs in both the Fuslsplra and 

 lure* beds at Lime City, Stcwartsvllle, Mantorvllle, Hader, and other localities. The original lyjies were 

 obtained In Wisconsin, and the species Is said to occur at many points In that state. Good casU have 

 been found In Pike county, Missouri. 



CoJfcetfwu. Geological and Natural History Survey of Minnesota; E. O. rirlch. 



Jfcsatm Register, Nos. 7345, 7485, 7842. 



Genus CCELOCAULUS, (Ehlert. 



Jfiireftisonia (part.) of LINDSTKOM, BII.I.IM;-. and other authors. 



Calexavlta <KHLERT (as subgenus of JfurcMsonia), 1888, Extr. Bull. Soc. d'Etud. Sclentlf. d'Angers, 

 p. 80. 



For generic characters see page 959. The date of this genus should be 1888 

 instead of 1887. 



This type of shells is not as closely related to Hormotonvi as may appear on a 

 hasty comparison. To the practised eye there is something peculiar about their 

 general aspect that at once causes them to be set aside as a group by themselves. 

 With few exceptions they are all very slender many-whorled shells, with a contin- 

 uous narrow umbilical perforation, the inner lip straight and the lower angle of the 

 aperture comparatively very little produced. The whorls are depressed, in two 

 instances our (C. negledus and C. barroisi (Khlert) probably not more than twelve in 

 number, generally exceeding fifteen, and in some cases as many as thirty. The 

 liitinl in all observed cases is wide and flat and lies beneath the middle of the whorls 

 of the spire. In at least some of the species a considerable number of the apical 

 whorls are filled with an organic deposit. 



