42 LOWER PENINSULA. 



Plate XVII. — Fig. 3 is a silicified specimen split in two, formed 

 of tube casts. Found on the shore of Lake Superior, at White- 

 fish Point. Among the pebbles of the same locality other speci- 

 mens of Alveolites are found, which agree with Alveolites squa- 

 mosus, Billings. 



ALVEOLITES SUBRAMOSUS, N. Sp. 



Incrusting expansions of irregular form, dependent from the in- 

 crusted object in the first stages of growth, subsequently of mamil- 

 late or digitato-ramose form. Orifices not over half a millimeter 

 wide, margined on the outer side with a convex projecting or a 

 flattened appressed lip ; denticulated by crests, one of which in the 

 median line of the inner body side of the tubes is much more promi- 

 nent than the others. Pores large, rather remote. Diaphragms 

 distant. Found in the Hamilton group of Thunder Bay, at Stony 

 Point, and other localities. In mode of growth it perfectly resem- 

 bles the branchlets from the Devonian strata of the Eifel, described 

 by Milne-Edwards under the name of Alveolites subequalis, but its 

 tubes are more minute and more strongly compressed than in that 

 form. 



Plate XVIII. — Fig. 4 represents calcified specimens from Stony 

 Point, Thunder Bay, etc. 



ALVEOLITES GOLDFUSSII, Billings. 



Undose, discoid expansions, with an imperfectly developed epi- 

 theca on the lower side, exhibiting the prostrate tube walls diverg- 

 ing from a central point of attachment. Orifices oblique to the 

 surface, rarely denticulated at the margins, but interiorly, spinulose 

 longitudinal crests are found well developed in polished sections. 

 The tubes are seen in various degrees of compression in the same 

 specimens ; usually their transverse diameter is twice larger than 

 their height, but sometimes tubes nearly as wide in one direction as 

 in the other, and almost erect, as in an ordinary Favosites, can be 

 observed. The size of the. tubes is larger than in Alveolites squa- 

 mosus, measuring in the larger diameter from one and a half to two 

 millimeters. 



