249 



Calpidium Busk, char, emend. 



The steiiuil (irca has 5 fenestrte disposed in a curve and an inner cryptocvsl 

 lamina. The aperture, the anter of which is surrounded hy a strongly projecting 

 margin, has a trilohed or triangular sinus ending in a [)oint, and is provided 

 with two very strong hinge-teeth, projecting within the aperture. The rosette 

 plates of the lateral chambers are placed in small rounded depressions and 

 may therefore he looked u[)on as multiporous. The occlusion lakes place in a 

 way similar to that in Sciiticella. 



In the two species of this genus the lateral chambers occupy much more 

 than one half of the surface of the single zoa'cia as well as of the bi- and tri- 

 zod'cial inlernodes. They occupy especially the greater \y,\r[ of the distal as well 

 as of the basal surface, l)eing separated here only by a number of elevated ridges, 

 each furnished with a longitudinal furrow. 



Calpidium ponderosum Goldstein. 



Catenicella ponderosa Goldsl., Journal Micr. Soc. Victoria, 1880, pag. 63. 



(t'l. X\I, figs. '):!— 5 0, t'l. Xtll, llgs. 1 n-1 d). 



The zocecia are o\al and the sternal area, which is longer by at least a half 

 than the aperture, is |)rovidcd with live large, ])ear-shaped fenestra separated by 

 narrow ribs, in the marginal portions of which a generally strongly developed 

 cryptocyst appears. Inside the sternal area is a large, obliquely oval cryptocyst 

 lamina. The aperture is oblong and .separated by a constriction into an anter, 

 the two lateral margins of which converge towards the constriction, and a tri- 

 angularly trilohed poster. The sternal sinus is mainly preserved in the form (jf 

 the small, triangular sinus of the aperture, but immediately on the proximal side 

 of it an extremely short sutural line is seen, in which two very slightly devel- 

 oped and somewhat [)rotruding ribs meet, ^^'ithin each of the two pi'occsses 

 bounding the constriction we see a robust, cylindrically conical hinge-tooth, which 

 however does not project freely into the aj)erture itself, when the latter is seen 

 from the frontal surface. The anter of the aperture is surrounded by a large, 

 obliquel}' protruding, bilobed, umbellate expansion, the two triangularly rounded 

 lateral halves of which are separated by a broad, but low, obtuse-angled 

 incision. 



The lateral chambers. The scapular chamber is not everywhere developed 

 as an avicularium, and the latter is not infrcciuenlly wanting on one side in the 

 single zooccia as well as in the bi-zocecial internodes. The three other lateral 

 chambers have a membranous roof and occupy a very large part of the surface 



