1020 THE PALEONTOLOGY OF MINNESOTA. 



ICoelocaulus oehlertl. 



Species whose known characters are in accord with this diagnosis of Ccelocaulus 

 occur in most of the principal formations from the Calciferous on to well up into 

 the Devonian system. Of these Murchisonia linearis Billings, is the oldest. Then 

 followed our C. cehlerti and C. neglectus, both Trenton forms, M. compressa Lindstrom, 

 from Upper Silurian strata in Gothland, M. bivittata, M. longispira, M. logani and 

 M. turritiformis, four Guelph species described by Hall, and C. davidsoni, C. barroisi 

 and C. procerus, three species described from the Devonian of France by (Ehlert. 

 And there are others which probably belong here, but they are as yet too little 

 known to justify their removal to Ccelocaulus. However, without them, the ten 

 species mentioned make a sufficiently respectable showing to establish the genus in 

 the classification of the Paleozoic Gastropoda. 



CCELOCAULUS CEHLERTI, n. sp. 



PLATE LXX, FIGS. 61-63. 



This species is known only from fragmentary casts of the interior, but as it is an interesting and 

 striking form we deem it well worth a description. The apical angle is about 12, and, if the taper of the 

 spire is uniform an entire specimen must consist of at least thirty whorls, and have a length of about 

 60 mm. The largest specimen, having a maximum diameter of 12 mm., has eight whorls in a length of 

 30 mm.; another, 9 mm. in diameter, has twelve whorls in the same distance. The bight of the whorls is 

 to their wi 1th as 2 is to 5 or 3 to 8. The whorls are very little separated and decidedly convex in casts 

 but in the shell itself, which evidently was very thin except at the sutures, the convexity must be consid- 

 erably less. Transverse section of whorls rounded quadranglar. Band and surface markings not observed, 

 probably obscure, since no trace of them is visible on a mould of the exterior. 



We know of no other shell in the Lower Silurian deposits of the Mississippi valley that could for a 

 moment be confounded with C. oehlerti. The next species is smaller and has a much wider apical angle, 

 with fewer whorls. 



Formation and locality. A. rare fossil of the Trenton group (Galena limestone), and so far known 

 only from Jo Daviess county, Illinois. 



Collection. E. O. Ulrich. 



CCELOCAULUS NEGLEOTUS, n. sp. 



PLATE LXXXII, FIGS. 29-31. 



Hight about 18 mm., apical angle about 25. The only specimen seen is a slightly distorted cast of 

 the interior, consist ing of only four whorls, the uppermost of which has an obtusely rounded termination, 

 indicating that the apical whorls were filled with an organic deposit. These four whorls have a hight of 

 about 12 mm., the last a diameter of 7 mm., the first of about 3 mm. The whorls are rounded in trans- 

 verse section, the sutures deep, the umbilical perforation small, yet very obvious. 



This small species might lie confused with Hwmotoma subangulata or with certain varieties of //. 

 gracilis, but if the observer will bear in mind that the umbilicus is very small and quite Inconspicuous in 

 casts even of those shells, that their whorls are not so much depressed nor subcircular in section, and that 

 the upper turns are never lacking except through accident, he should not have much trouble in disting 

 uishing the Coelocaulrts. 



Formation and locality. Clitambonites bed of the Trenton group, near Cannon Falls, Minnesota. 

 Collection. E. O. Dlrich. 



