EUPLECTELLA. 43 



tlie accessoria. Of the latter, again, those that occur closely 

 bundled together in association with the rays of the priucipalia, 

 are called the comitalia. Other accessoria are situated in a 

 nearly or quite loose and irregular arrangement. 



In Eyplcc-tclla, an imi^ortant portion of the parenchymalia 

 goes into the formation of an exquisitely lattice-like framework, 

 the ground skeleton, extending throughout the entire lateral wall 

 (PI. II, fig. U). It consists of the three well-known systems of 

 beams or spicular bundles. The longitudinal and the more in- 

 wardly situated circular systems of beams have for their common 

 priucipalia either large oxystauractins or oxypentactins (some- 

 times oxyhexactins with a small sixth ray). These are always 

 so situated that the spicular center lies at the intersecting point, 

 while of the two cruciately disposed complete axes, one goes into 

 the composition of the longitudinal, and the other into that of 

 the circular, beams. Herein is given the condition of the courses 

 taken by the two beams just referred to. The fifth ray, if present, 

 is radially and distal ly directed and may freely project out of 

 the external surface. Should it be found desirable to divide the 

 present Eupledella into two subgenera or distinct genera, I think 

 the presence or absence of this distal ray ought in the first in- 

 stance to be taken into consideration as a distinguishing charac- 

 teristic. In those priucipalia, in which the transverse axis goes 

 into the uppermost circular beam at the junction of the lateral 

 wall with the sieve-plate, the superiorly directed ray may be en- 

 tirely wanting or may be shortly developed and extended into 

 the sieve-plate beams. Moreover, these priucipalia may frequently 

 possess a short distal ray entering into the cuft', even though 

 they be without such a ray in other positions of the wall. 



The comitalia to the priucipalia above mentioned are pre- 



