28 F. A. SMITT, 



a row, the one above the other, they give the margin of the branches that serrulate 

 appearance, whence I have taken the specifical name of this species. 



In the construction of the zooecia, as they appear when young (figs. 116 and 121), 

 all the Porinidan characters are plainly expressed. With the exception of the cha- 

 racteristical median pore, all the primary pores of the ectocyst soon are closed, the 

 calcification, in going forth, thus giving the zooecial wall a reticulated appearance which 

 again is rendered porous by the thickening of the walls of the meshes x ). Then the 

 furrows between the zooecia are filled up, and, at the same tirne, the calcification gives 

 a very different, usnally transversely-ovate, secondary form (fig. 124, c — é) to the pri- 

 marily semielliptical aperture of the zooecia, until these, also, at last are closed. The 

 median pore in the same manner is vanishing, bnt the small, lateral avicularia, like 

 the greater, spathulate ones, are uplifted by the layer of calcification, and, though they 

 change their place and direction, they, usually, will be observed even on the lower parts 

 of the stem, where the other colonial organs are overgrown. This calcification does 

 not always produce any uniform layer, but particularly round the aperture of the 

 zooecia and below the avicularia it grows thicker, and the eminences thus formed, in 

 running irregularly together, at last, on the lower parts of the stem, produces the ap- 

 pearance, as shown by the fig. 118. 



Porina subsulcata n. sp.? (Pl. VI, figs. 136 — 140). 



Char.: Porina erecta, ramosa, ramis planatis (låtit. =-- 1,5 mm. circ.) structuram 

 individuorum prsebet Porince (Eseharce) sulcatce (M. Edw.). 



Descr.: Zooecia primaria elongata, ovato-cylindrica, frontem praäbent convexam, 

 aperturam semiellipticam (lat. = 0,09 mm. circ), porum medianum rotun- 

 dum, margines prabent poris perforatos. Supra frontem primariain linea 

 calcificationis elevatur granulosa, in parte zooecii proximali simplex, me- 

 diana, in media fronte bifurcata latus utrumque apertura? petit, quomodo 

 area pone aperturam formatur triangularis, qua? porum medianum et avi- 

 cularium acutum ad marginem proximalem aperturaa positum, distaliter 

 versuin, amplectitur. Implentur deinde, calcificatione progrediente, spatia 

 interlinearia supra limites zoceciorum, poris marginalibus evanescentibus, 

 relicto solum sulco limitari. Depressa tunc area zooecii secundaria aperturam 

 pra3bet profunde positam, reniformem, pro aviculario supra illam projecto. 

 Calcificatione jam longius progressa formantur avicularia nova, structuram 

 anteriorum aimulantia, proximaliter versa, supra partem proximalem zoce- 

 ciorum. Obducuntur deinde area? zoceciorum, evanescunt avicularia ad 

 aperturam, clauduntur aperturse porique mediani. 



Ad margines ramorum colonias avicularia formantur majora, acuta, 

 qusB mandibulo triangulari clauduntur. 



l ) In the living state, these pores are closed by a shining membrane, and then,, when dried, the stem has a 

 glossy surface; in the dead state. when dried, the pores are open, and the surface of the stem is more 

 dully white. 



