JAMKS TYPES OF BRYOZOA-BASSLER. 55 



Leptotrypa ? dyvhei Nickles and Bassler, Bull. U. S. Geol. Surv., No. 17.3, p. 298. 

 Stigmatella (h/Hiei tJLRicH and Bassler, Smithsonian Misc. Coll. (Quart. Issue), 

 XLVII, 1904, pi. X, fig. 11. 



Both the internal and external features of this species have been 

 figured by its author satisfactorily enouj^fh for its recognition, and 

 additional illustrations of the internal structure are given here only to 

 bring out points not mentioned by James nor shown in his figures. 



The zoarium is an expansion loosely incrusting crinoid columns and 

 sometimes attains considerable size, the type specimen being about 

 180 mm. in length and varying from a minimum diameter of 5 mm. at 

 the ends to a maximum of (30 mm. 



In vertical sections the noticeable features are the almost complete 

 absence of diaphragms and the development of the acanthopores in 

 zones, the latter feature in combination with the former being the 

 principal characteristic of the genus Sit'ujinateUa. Tangential sections 

 passing through one of these zones of acanthopores exhibit these struc- 

 tures of a fair size at the zooecial angles, but a .section through an}^ other 

 part of the zoarium shows thinner- walled zooecia with the acanthopores 

 either very small or not present at all. 



The loosely incrusting method of growth, thin-walled angular zocecia 

 with mesoporos practically wanting, the development of acanthopores 

 in zones and the almost entire absence of diaphragms are characters 

 causing this species to be easily recognized. 8. davk (Ulrich), a 

 common and highly characteristic fossil of the Eden shales, also grows 

 on crinoid colunms, but it can not be confused with S. dyche!., its 

 zoaria being much smaller and the surface nearl}^ always spinulose. 



Occurrence. — A highly characteristic although somewhat uncommon 

 fossil of the Mount Auburn member of the McMillan formation at 

 Lebanon and other localities in southwestern Ohio. 



STOMATOPORA DELICATULA (James). 



Plate III, figs. 4-7. 



Hippothoa delicatula J AMv:s, Paleontologist, No. 1, 1878, p. 6. 



Stomatopora delicatula Nickles and Bassler, Bull. IT. S. Geol. Surv., No. 173, 1900, 



p. 419. 

 Stomatopora proutaua Miller, Jour. Cincinnati Soc. Nat. Hist., V., 1882, p. 39, 



pi. I, figs. 4-4b. 

 StomatoporajywutanaVhRicn, Geol. and Nat. Hist. Surv., Minnesota, Final Rep., 



Ill, Pt. 1, 1893, p. 117, pi. I, figs. 8-12. 

 Rhopidonuria ■pertenuisV'V.B.wn, Fourteenth Ann. Rep. (ieol. and Nat. Hist. Surv., 



Minnesota, 1886, p. 59. 

 Stomatopora (enuissima Ulricm, Jour. Cincinnati Soc. Nat. Hist., XII, 1890, 



p. 175, fig. 2. 

 Stoniatopora delicatula-tenuisximd Nicklks and Bassler, Bull. U. S. Geol. Surv., 



No. 173, 1900, 9. 419. 



Original description. — "Polyzoary creeping, adnate, branching 

 dichotomously, and sometimes anastomosing. Branches linear, about 



