32 GEOLOGICAL AND NATURAL HISTORY SURVEY OF CANADA. . 



small but well marked groups of species, each indicating relations to 

 widely different families. Trie first or typical section, including, ap- 

 parently, only D. petropolitana, D. Wtstoni, and one or two undescribed 

 species, is characterized by comparatively large zooecia, more or less 

 wavy walls, and a resemblance to true species of Monotrypa {e.g. M. 

 undulata, Nicholson and M. siibglobosa, Ulrich) that, in my opinion, 

 amounts to real affinity. Monotrypa itself comprises two very different 

 sections, such species as M. fiiiasa, d'Orbigny, M. petasiformis, Nichol- 

 son, M. irregularis, Ulrich, and M. montlcula, White, being true Amplex- 

 oporidoi^ with very close relations to Leptotrypa, while the typical 

 section of the genus presents no very great affinity with any of the 

 families proposed by me. 



Batostoma, a genus that has given me no little trouble to place, I am 

 now convinced, is, (especially in its aberrant members, of which several 

 are known to me) more intimately related to the typical sections of 

 both Diplotrypa and Monotrypa than any of the others. The obvious 

 relationship between these three groups strongly suggests the erection 

 of a new family, which may be known as the Diplotrypid/e, the genus 

 Diplotrypa being selected as the type. By establishing this family, 

 three troublesome genera are satisfactorily placed, and the families com- 

 prised in the amended classification of the Tre^os^oma^a proposed in my 

 forthcoming work on Illinois bryozoa assume a degree of definition 

 and compactness which they would not possess otherwise. With this 

 happ3^ result comes another less fortunate, a reconstruction of Diplo- 

 trypa and Monotrypa being necessitated thereby. Thus, the second 

 section of Diplotrypa, comprising D. regularis, ¥oord, D, infida, Ulrich, 

 D. patella^ Ulrich, (Kept. 111. Geol. Sur., vol. YIII.) and, perhaps, D. 

 Whiteavesi, Nicholson, approaches very near to Prasopora, and ought to 

 go with the Monticuliporidte. That disposition, however, would necessi- 

 tate the adoption of one of two courses, — either a new genus would 

 have to be established for their reception, or the species would have 

 to be placed under Frasopora, — neither of which I am prepared to 

 adopt. More study and very detailed comparisons are required 

 before I shall consider myself justified in proposing a final arrange- 

 ment. In the meantime it is best to leave these species with Diplo- 

 trypa. D. Milleri, Ulrich, a Niagara species with a decided leaning 

 toward the Calloporidae, should likewise remain in its original associa- 

 tion, while the same course may be pursued, provisionally, with the 

 species at present referred to Monotrypa. 



