CORALS AND BRYOZOA. 199 



The elongate depressed maculaB resemble those of L. alveata of the Upper 

 Helderberg group, but the species may be distinguished as follows ; the cell 

 apertures are on a plane with the surface ; the peristomes are equally elevated, 

 are not denticulated and the apertures do not distinctly radiate from the maculae. 

 The cell apertures, in form and size, very closely resemble those of L. ovata of 

 the Upper Helderberg group, but it presents the following differences ; the 

 peristomes are equally elevated, are not denticulated, the maculae are narrow, 

 elong<ate, depressed, the apertures nearest the maculae are not larger than the 

 others, and sometimes do not radiate from them : from L. substellata it is dis- 

 tinguished by the narrow elongate maculae, the obscure radiation of the aper- 

 tures and equally elevated peristomes : from other species of this geological 

 formation it is distinguished by the narrow, elongate-depressed maculae, uniform 

 size of apertures and non-radiation from the maculae. 



Formation and localities. Hamilton group, shore of Canandaigua lake, Ontario 

 county ; York, Livingston county, and four miles south of Le Roy, Genesee 

 county, N. Y. 



LiCHENALIA RAMOSA, n. sp. 



HOT FIGURBD. 



ZoARiUM ramose, hollow, branches very frequent, diameter from 4 to 10 mm., 

 thickness of frond from .50 to 2 mm.; the inner surface is a concentrically 

 wrinkled epitheca. Cell tubes rectangular or oblique to the surface ; septa 

 very infrequent or entirely wanting. Intercellular space vesiculose ; the 

 vesicles are large and irregularly disposed near the base, they are smaller 

 and more regularly superimposed above, but not having the appearance of 

 walled, septate tubuli, from four to eight vesicles in the space of 1 mm , 

 measured longitudinally. Cell apertures nearly circular, diameter .25 mm., 

 irregularly disposed, generally separated by less than the diameter of an 

 aperture and frequently in contact. Peristomes thin, scarcely elevated, and 

 having on one side two slight denticulations. Interapertural space gently 

 convex, granulose. Surface marked by circular, granulose maculae, destitute 

 of cell apertures, the centres of which are distant about 3 mm., and their 



