102 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.81 



gential rays 80/x to 240/x; and of the distal rays YO/i to 200/i. At the 

 base the thickness averages about 10/a. The rays taper gradually 

 toward the pointed ends and may all be nearly equally rough, on ac- 

 count of microspines, but more pronouncedly so at the distal ends. 

 These hexactins are generally arranged irregularly, and do not 

 form a continuous quadrate-meshed latticework. 



The oxyhexasters, occurring in moderate abundance in all parts, 

 are partly normal and partly hemihexactinic and hexactinic forms. 

 In most normal oxyhexasters (fig. 13, c) the principals each bear 2 

 or 3 terminals, so that the total number of terminal points is 12 to 

 16. Their diameter measures 110/x to 140/x. The terminals are 

 rather strong, measuring about 2/i, across at the base, and are straight 

 or wavy and sparsely rough on the surface. The principals are 

 extremely short and often obsolescent. Throughout the parenchyme 

 there are numerous oxyhexasters and hemihexactinic (fig. 13, d, e) 

 and hexactinic (fig. 13, /, g) forms, which are seen to be sparsely 

 rough or occasionally densely rough, having numerous micro- 

 tubercles on the surface and measuring 112/x in axial length. Any 

 one of the principal rays of hemihexactinic form may bear two 

 long, straight or wavy, divergent, sharply pointed terminal rays, 

 thus giving rise to the oxyhexasters, so that all gradations between 

 the 6 and 12 rayed spicules are seen. These several forms are en- 

 tirely similar to those occurring in Staurocalyptus dowlingii 

 (Lambe) . 



The discoctasters (fig. 13, A) are not abundant. They are slender 

 rayed and on the whole small. The diameter is usually 80/x. The 

 central node is plain and very weakly tubercled. The principals 

 are slender, nearly as long as, or much longer than, the terminals. 

 The number of terminals to a principal is frequently three and 

 probably never more than four. They form a very slightly diverg- 

 ing tuft and are nearly straight. On the minute terminal disks 

 the marginal serration is wanting. 



Malformed discoctasters, in which one or more primary terminals 

 stand free without fusing with any of the secondary principals, are 

 of occasional occurrence. 



The microdiscohexasters are of usual appearance and 50)u, in diam- 

 eter. They are found, mostly in the ectosome and in the endosome, 

 in fairly large numbers though scattered. 



The new species, as before mentioned, resembles Staurocalyptus 

 dowlingii in outer configuration and in some essential points of 

 spiculation, but differs from it in having a smaller discoctaster and 

 a larger microdiscohexaster. 



