148 LOWER PENINSULA. 



ZAPHRENTIS GREGARIA, N. Sp. 



Short turbinate, somewhat curved polyp cells, of about two inches 

 calyx diameter by a length of from one and a half to two and a 

 half inches. Surface annulated by sharp transverse wrinkles and 

 distinctly ribbed by longitudinal septal furrows. Calyces spacious, 

 with broad subplane bottoms, over which the lamellce extend to the 

 centres. A large septal fovea generally on the convex curved side. 

 Side walls of calyces suberect with acute edges. Found in large 

 numbers in the black shaly limestone strata of the lower part of 

 the Hamilton group, on the shore of Lake Huron, north of Thunder 

 Bay. Not represented. 



Another form of Zaphrentis found in the Hamilton group of 

 Arcona, C. W., may be mentioned here. Some of the specimens 

 perfectly resemble Zaphrentis prolifica of the Helderberg group ; 

 other larger specimens, externally identical with them, have the 

 bottoms of the calyces formed by broad, perfectly naked, flat, or 

 somewhat concave diaphragms. They seem to be mere individual 

 variations of one and the same type^ first represented under the 

 form of Zaphr. prolifica. 



ZAPHRENTIS CONIGERA, N. Sp. 



Compare AULOPHYLLUM, Milne-Edwards. 



Long, horn-shaped, conico-cylindrical polyparia, with obtusely 

 annulated rugose surface, attaining a size of one foot in length by a 

 diameter of one and a half inch. Calyx deep, with erect side 

 walls and acute margins, surrounded by about 120 alternately larger 

 and smaller lamellce ; sharp linear crests in the inside of the calyces, 

 lowered into rounded rugce on the margins. The bottom of the 

 calyces is reflected and forms a large pointed cone with broad base, 

 on which the central ends of the radial crests ascend with a spiral 

 twist. Septal fovea comparatively small, irregular in position re- 

 garding the curvature of the horn-shaped stems. The central cones 

 are the analogon of the transverse diaphragms, which are invagi- 

 nated into one another, and become superficially attached by 

 their crests, but do not combine into a continuous axal column. 

 From an observation of the figures of Clisioph. prolapsum. 



