CAMBRO-SILURIAN MICRO-PAL/EONTOLOGY. 37 



Monticulipora redangularis, Whitfield, 1878, Annual Rep't. Wis. Geol. Sur., p. 70. 

 " " " 1882, Geol. Surv- Wis-, vol. 4, p. 294, pi. 



44, figs. 11-12. 

 " {Monotrypa) quadrata, Nicholson, 1881, genus Monticulipora, p. 



179, fig. 36. 



The collection contains several fragments of this highly characteris- 

 tic and persistent species. It is not only an easily recognized form, 

 but it is also to be found more or less abundantly v^rherever its proper 

 horizon (the upper beds of the Hudson Eiver or Cincinnati group) is 

 exposed, making it an excellent guide in stratigraphical correlations. 



The principal characters of the species are the thin walls and quad- 

 rate rhomboidal or hexagonal form of the zooecia. In transverse sec- 

 tions of a branch the tubes are always largely four-sided. 



The Manitoba specimens were collected by Mr. T. C. Weston at Stony 

 Mountain in 1884. 



FiSTULIPORA ? LAXATA. (N. Sp.) 



PI. VIII., figs. 2, and 2a. 



Zoariura massive, probably of hemispheric shape with the under side 

 concave and covered with a wrinkled epitheca. The only specimen 

 seen is a broken mass sixty mm. thick and about 120 mm. wide. From 

 its shape I should judge its complete diameter to have been not less 

 than 170 mm. The surface is too much weathered and obscured by 

 adhering rock to show the minute superficial characters. Good thin 

 sections, however, bring out the more important internal structure in a 

 very satisfactory manner. 



Transverse sections exhibit the usual characters of species of Fistuli- 

 pora, only there is an unusual irregularity and looseness in the arrange- 

 ment and size of both the zooecia and interstitial vesicles. The zooecia 

 are irregularly ovate in cross-section and have thin walls. The 

 lunarium, though never a very marked feature, is always determinable 

 by the semi-circular , shape of one-half of the circumference of the 

 zooecium, the other half being, if not angular, at any rate always drawn 

 to a circle of greater diameter than is the usually smaller and always 

 more regularly curved lunarial side. A zooecium of the average size 

 measures about four-tenths of a millimetre in length by three-tenths 

 of a millimetre in width; eight to ten occur in a distance of five mm_ 

 The vesicles vary greatly in size and distribution, some being very 

 small and others as large and even lai-ger than the zooecia, and 

 f?carcely distinguishable from them. They form, generally, but a 



