May, 1922.] 



The Canadian Field-Naturalist 



85 



spicuous markings. The inner walls are convex 

 toward the interior, and, in certain species, 

 present a short central spine projecting toward the 

 center of the cavity. In the Escanaba specimen 

 the inner walls do not appear to be preserved. 



It is possible that two genera occur among the 

 species formerly referred to Pasceolus. Bassler 

 refers the two species from the Gun River member 

 of the Anticostian series of strata, Pasceolus gre- 

 garius Billings and Pasceolus intermedius Billings, 

 to the genus Nidulites; however, the reason for 

 this association is not stated. 



The Escanaba specimen of Comarocystites 

 punciatuts Billings retains 22 complete thecal 

 plates. Among these is the plate bordering the 

 anal opening on the right, and the one bordering 

 it on the left is almost entire but has been crowded 

 against the former. A part of the basal support 

 of the pair of brachioles nearest the anal opening 

 is present; and a trace of the basal support of 

 the second pair of brachioles, more distant from 

 the anal opening, may be detected. Below the 

 level of these basal supports for the brachioles 

 the thecal plates best preserved are arranged in 5 

 transverse rows, with indications of 2 rows 

 beneath. Evidently two or three additional 

 transverse rows of plates must have intervened 

 between the lowest part of the specimen and the 

 top of the column. Along the level of the anal 

 opening and just beneath the latter, the number of 

 thecal plates in the transverse rows is 6 or 7, 

 indicating that nearly the entire width of the theca 

 is presented, but pressed flat previous to fossiliza- 

 tion. In this flattened condition 6 plates form a 

 width of 35 mm. The plates are of the same 

 size as in typical Comarocystites punctatus, and 

 present the same degree of concavity, but appar- 

 ently are much thinner than in most specimens 

 found at Ottawa. The plates are built up of 

 vertical lamellae occupying triangular fields whose 

 apices meet at the centers of the plates, and 

 whose bases are formed in each field by one of the 

 sutures between adjacent plates. About 10 of 

 these vertical lamellae, parallel within the same 

 field, occupy a width of 3 mm. The pores between 

 the lamellae tend to be arranged in transverse rows, 

 but with numerous irregularities. Several of the 

 plates preserve some of the pustulose elevations 

 noted on the exterior surface of the thecal plates of 

 typical specimens of this species (Ottawa Natur- 

 alist, 30, 1916, pi. 2, figs. lA, IB, and ID.). 



Aside from the occurrence of the typical species 

 at Ottawa and on the Escanaba river, Comaro- 

 cystites is known only from the Kimmswick 

 member of the Black River formation at Cape 

 Girardeau, Missouri, and at West Kimmswick in 

 the same state, where it is represented by Comaro- 

 cystites shumardi Meek and Worthen. 



Pasceolus globosiis, on the contrary, is more 

 widely distributed. It is listed by Ulrich from 

 the lower or Clitambonites member of the Prosser 

 formation in the Minnesota area (Geol. Survey 

 Minnesota, III, pt. 2, page cxxiii); and it occurs 

 in the upper of Cynthiana member of the Trenton 

 near Ivor, east of Cinncinati, Ohio, although the 

 latter horizon is much higher than any part of 

 the Trenton in the Ottawa area. 



Among the genera known at present in the 

 Trenton only from Ottawa and Kirkfield in 

 southern Ontario are Astrocystites, Atelocystites, 

 Glypfocystites, Ottawacrinus, Palseocrinus, Peri- 

 glyptocrinus, Petraster, and Protaxocrinus. Of 

 these Palseocrinus is known as far east as Montreal 

 during the Chazyan, but not during the Trenton. 



Among genera known in the Trenton of Canada 

 only from Ottawa and Kirkfield, but occurring 

 also in the Curdsville member at the base of the 

 Trenton in Kentucky, are Amygdalocytsites, 

 Cleiocrinus, Edrioaster, Glyptocrinu s , Hybocrinus 

 Hybocystites, Lebetodiscus, Reteocrinus, and Sten- 

 aster. Among these, Cleiocrinus occurs in the 

 Chazyan of Lake Champlain and of western 

 Tennessee, and Hybocrinus occurs in the Chazyan 

 of Montreal. Edrioaster ranges in the Trenton 

 as far west as the Minnesota area, where it is 

 listed by Ulrich from the Prosser member. Poro- 

 crinus occurs not only at Ottawa, Kirkfield, and 

 Belleville in southern Ontario, but also in the 

 Platteville member of the Black River formation 

 in Illinois, and in the Trenton of Frobisher Bay, 

 in Baffin Land, in Arctic America. Hemicystites 

 occurs at Peterboro, but in Kentucky it is known 

 only in the upper or Cynthiana member of the 

 Trenton, above the Trenton of the Ottawa area. 



Among the genera occurring not only at Ottawa, 

 Kirkfield, and in central Kentucky, but also as 

 far east of Ottawa as Montreal are Cupulocrinus 

 Dendrocrinus, Ectenocrinus, Hudsonaster, Pleuro- 

 cystites, and Tseniaster, the last mentioned genus 

 occurring near the city of Quebec. Archx- 

 ocrinus and Cheirocrinus are known from as far 

 east as Montreal, but are not listed from Kentucky. 

 Of these genera Cupulocrinus, Dendrocrinus, 

 Hudsonaster, Pleurocystites, Tseniaster, and Cheiro- 

 crinus are known also in the Trenton of New 

 York, while Hudsonaster ranges as far west as 

 Minnesota. 



Cyclocystoides is not known at Montreal, but 

 occurs at Lake St. John, in northern Quebec, and 

 the type of Cyclocystoides anteceptus Hall was 

 obtained on the Escanaba River in the northern 

 Peninsula of Michigan. The genus is known also 

 from New York. 



Among the genera known from Ottawa and 

 Kirkfield, and also in New York, are Carabocriniis, 

 Cremacrinus, and Urasterella. The fijst two of 



