11 



Stigmatella incrustans, Cumings and Galloway. — Several examples of a 

 bryozoan have been found in the Homotrypa streetsvillensis zone of the Streetsville 

 member of the Richmond,, which are referred to S. incrustans of the Liberty of 

 Indiana. They incrust crinoid columns and brachiopod and pelecypod shells. 

 Many forms of incrusting bryozoans, referred to the genus Stigmatella, are 

 very close to one another in their relationships;- among this number are: S. 

 incrustans, S. sessilis, S. clavis, and S. nicklesi. S. incrustans is distinguished 

 by the possession of monticules and by its loose, irregular habit of growth. 

 See Plate VI, Figure 7. 



Stigmatella interporosa, Ulrich and Bassler. — A fragment of a ramose 

 bryozoan was found in the Streetsville member which is herein referred to 

 S. interporosa. This species, according to Cumings and Galloway resembles 

 S. catenulata, being distinguished from that species by the less robust growth 

 and thinner mature region, by the weaker development of chain-like mesopores, 

 and by the greater number of these mesopores. According to Ulrich and Bassler, 

 S. interporosa occurs in the Waynesville of the Cincinnati basin. 



Stigmatella cf. lambtonensis , Parks and Dyer. — Two or three specimens 

 which resemble this species were found in the Erindale member. In the original 

 description of the species, S. lambtonensis was distinguished from S. sessilis, 

 Cumings and Galloway, by a difference in growth. The latter species is incrust- 

 ing and forms rather delicate discs, while the former is not incrusting and forms 

 coarser, more irregular zoaria. Internally, the two species are identical. It is 

 possible that future study will show that the two species are identical, or more 

 probable still that S. lambtonensis is identical with the variety Stigmatella sessilis 

 crassa, of the Credit member of the Dundas formation. See Plate V, Figure 8. 



Stigmatella catenulata var. B., Parks and Dyer. — A single example of this 

 variety was found in the quarry at Port Credit, incrusting a joint of the column 

 of Lichenocrinus sp. The zoarium of the Credit River form is less robust than 

 that of the type specimen from the Humber member of the Dundas formation, 

 and the development of the chain-like mesopores is not so great. In these 

 features it is more like S. sessilis crassa of the Credit member. It agrees, 

 however, with the type of S. catenulata var. B. in the neat regular growth about 

 a crinoid column. 



There is evidently very little difference between certain species of the genus 

 Stigmatella of the Dundas and Richmond formations. When more material is 

 procured and a further intensive study made upon the genus, it may be found 

 that S. catenulata, S. sessilis crassa, S. lambtonensis, S. cf. clavis, and S. in- 

 crustans are variants of single species. On the other hand, 5. crenulata, at 

 least the form found on the Credit river, S. hybrida, S. interporosa, and S. 

 personata seem to be better defined species. 



Stigmatella sessilis crassa, var. no v. — See page 28. 

 Stigmatella personata lobata, var. nov. — See page 28. 



Brachiopoda 



Catazyga headi, Billings. — This species undoubtedly occurs on the Credit 

 river, but no good examples of full-grown forms have been found during recent 

 investigations. Several typical examples were found by Joseph Townsend 

 and are now in the collections at the University, labelled as coming from Streets- 



