204 ANNALS NEW YORK ACADEMY OF SCIENCES 



Pycnopora hirsuta sp. nov. 



Zoarium in the form of a very thin expansion. Thickness .14 mm. 



Zooeeia prostrate and thin-walled below for a short distance, thick-walled 

 and erect at the surface. The apertures are rounded, more or less elongated, 

 rather regularly arranged in quincunx, about 7 or 8 in 2 mm. (7 in the direc- 

 tion of their longitudinal diameters). They are about .21 mm. long and from 

 .11 to .14 mm. wide. The mesopores are small, rounded, distributed one or 

 two at a time in the angles between the zooeeia. Walls thick, the intervals 

 between the zooeeia being from one fourth to one half the shorter axis of the 

 latter or about as thick as the average mesopore. Acauthopores very numer- 

 ous, imbedded in the walls, occasionally indenting the cells, to which they 

 then give an irregular and undulating outline, medium-sized to large, often 

 10 or 12 around a zooecium. In some areas, the acauthopores are much larger 

 than in others, and I believe that this is not due to distance from the surface. 

 Tabulje very rare in the zooeeia and absent from the mesopores. 



Stenocladia subgen. nov. 



Zoarium in the form of bifoliate fronds which branch and perhaps inoscu- 

 late. A median plate is probably lacking. In no instance can the presence 

 of such a structure be demonstrated, and usually there is no trace that could 

 be so construed. 



Zooeeia elongated, slender and longitudinal in the median portion of the 

 frond ; considerably larger and perpendicular to the surface at maturity. The 

 walls are thin in the immature zone, thickened near the surface. Mesopores 

 fairly abundant, variable in distribution, occasionally forming large groups 

 or maculfe. Acauthopores moderately abundant, small, not greatly indenting 

 the cells. Zooeeia and mesopores thin-walled and angular to near the surface, 

 where the deposit of selereuchyma closes the mesopores completely or in large 

 part and gives the zooeeia a circular or oval shape at the same time diminish- 

 ing their caliber. The acauthopores also are metamorphosed nor do they 

 project as spines. The walls at the surface appear to be marked by granular 

 dots of several sizes, the larger ones distributed down the center of the walls, 

 the smaller ones more marginal. The acauthopores have conspicuous tubular 

 axes which proceed in straight lines to the surface. In addition to these 

 structures, the walls in sections at right angles to the surface show many 

 fiber-like lines of denser material which appear to curve and divide, seldom 

 being normal to the surface. There are thus three fairly distinct zones on 

 each side : an axial zone, a superficial zone in which all the structures are 

 modified by sclerenehyma and an intermediate zone in which the zooeeia. ncan- 

 thopores and mesopores have their more usual characters. 



Type. — Stenocladia frondosa. 



Although presenting many analogies to the type of structure which I 

 have included under Idioclema. it seems probable that this must be re- 

 garded as having widelv different affinities. The most marked resem- 

 blances are found in the wall structure, with its inosculating fibers and 

 granulose, strikingly tubulated acanthopores. On the other hand, we 



