DESCRIPTIONS OF SPECIES. 83 



the ends of the longer transverse axis, and those standing immediatel)" next 

 to these have become wider than the others. Along the edges of each 

 wider costa is a double row of granulations, one on each side of the svim- 

 mit. Where I could find granulations along the summits of the narrower 

 costse there was only a single row. On the sides of the costse are the 

 striations already noted. 



Passing to the septa: There are 34 septa; on one side of a vertical 

 plane through the longer axis of the calice there are 15, while on the other 

 side there are 17. This asymmetry is surely only temporary. The thick- 

 enings of the septa near their inner termini have progressed so far that they 

 have fused to a considerable extent and have formed an apparent lamina 

 on each side of the real columella, which is very distinct and absolutely 

 tyjjical. 



The last stage would probalily be represented by the large specimen 

 already noted, and whose measurements are given. (PI. V, fig. 22.) 



The base of this specimen is broken, so it can be seen that it is solid. 

 The costse at the termini of the longer transverse axis of the calice and 

 those standing next have become decidedly wider than the others. In fact, 

 the three costse nearest each end of the longer transverse axis on each face 

 are wider than those on and near the median portion of the lateral faces. 



There are now 40 costaj and a corresponding number of septa. The 

 last eight costse have arisen, one on each side of each costa, standing on 

 each side of each secondary costa at the ends of the shorter transverse 

 axis of the calice. 



The descent of the costse and corresponding septa can be summarized 

 thus : 



First cycle + second cycle 4+4 



Third cycle, ou cacli side of each member of first cycle 8 



Fourth cycle, on each side of the four that stand next the secondaries on the 



middle of the lateral faces 8 



Fifth cycle, ou each side of the four quaternaries that stand next the secondaries 



on the middle of the lateral faces 8 



Sixth cycle, introduced iu same relative position 8 



Total 40 



By an examination of the figures most of these features can be dis- 

 tinctly seen. New septa and new costse are introduced at fom- points only, 



