MICEASTERIAS. Ill 



incisions between the lobes very narrow and linear; 

 polar lobe narrowly cnneate with concave sides, not 

 projecting, apical margin generally slightly retuse, 

 with a fairly deep median notch, angles on each side 

 of median notch apiculate, outer angles commonly 

 emarginate (sometimes only apiculate) ; lateral lobes 

 fairly equal and broadly cuneate, with a deep and 

 linear primary incision dividing each lobe into two 

 equal lobules, each lobule with a secondary incision 

 (not very deep) and generally with two tertiary in- 

 cisions, four ultimate divisions of each lobule emar- 

 ginate or bidentate (sometimes the tertiary divisions 

 are absent so that each lobule is only subdivided into 

 two parts, which are then tridentate or quadrideiitate) ; 

 with three projections across the base of the semicells, 

 the middle one conical and rounded or apiculate, the 

 lateral ones attenuated and elongate, curved outwrds, 

 and emarginate or bidentate at their apices ; with a 

 conical tooth within the base of each lateral lobe and 

 one within the base of each lateral lobule, also with 

 two, one above the other, within the lower half of the 

 polar lobe, all these teeth being directed outwards. 

 Side view of seniicell narrowly pyramidate, with a 

 rounded basal inflation on each side, apex truncate, 

 lateral margins each with two outwardly-directed, 

 acute projections. Vertical view fusiform, poles acute, 

 with three projections on each side towards the middle, 

 the median projection conical and obtuse or apiculate, 

 the lateral projections very much curved towards the 

 poles and generally bidentate, lateral margins towards 

 the poles serrate. Cell -wall smooth or delicately 

 punctate. 



Zygospore globose, furnished with stout, furcate 

 spines. 



Length 174-202 p,; breadth 136-180 /*; breadth 

 of isthmus 21-23 /x; thickness without projections 

 34-39 /A, with projections 53-57 /x. 



EXGLAXD. Angle Tarn, Cumberland ! Bowness, 

 Westmoreland ! (Bissetf). Malham Tarn Bog, \Y. 



