REPORT ON THE HEXACTINELLIDA. 127 



regularly developed discohexasters are of by uo means rare occurrence. These are 

 provided with numerous (eight or more) prong-bearing, long, terminal rays, which are 

 placed upon the terminal expansion of the short smooth principal ray, and do not differ 

 essentially in other respects from the rays of the discohexacts (PL XXV. fig. 6). It is 

 remarkable that these many-rayed discohexasters lie almost exclusively under the 

 surface of the disc, and that scattered between them similar rosettes occur, with a few 

 (often only four or three, or even two) pronged terminal rays on every principal. One 

 can detect a tolerably continuous series of transitions between the simple pronged 

 hexacts and those many -rayed discohexasters. 



Sometimes I also observed rosettes with numerous long, smooth, pointed, terminal 

 rays, i.e., oxyhexasters. The terminal rays are inserted on a terminal expansion of the 

 short principal rays like those of the discohexasters. 



The slight differences in the numerical proportions of the discohexacts and disco- 

 hexasters, in the thickness of the terminal rays and in the dii'ection of the same, which 

 are discoverable between the smaller fungiform specimens and the larger forms with lens- 

 shaped bodies, I regard as insufficient for the differentiation of particular species. 



The dermal skeleton resembles very much that of Caulophactcs latus. Here, too, the 

 proximal ray of the pentact hypodermalia is usually beset with prongs (PL XXV. fig. 8), 

 and the autodermalia are hexact pinuli with broad, short, fir-cone-like outer rays, 

 while their slightly conical transverse rays and the similarly formed proximal ray only 

 exhibit a sUght irregularity of surface on the terminal portion (PL XXV. fig. 5). 



The gastral skeleton lying on the convex upper side diff'ers from the corresponding 

 skeleton of Caulophacus latus only in the fact that the autogastralia are not pentact 

 but hexact pinuli, in which both the developed proximal, and the four transverse rays, are 

 smooth and only slightly rough on the extremity, while the freely projecting, scaly, pronged 

 distal ray is not so narrow and pointed as in the latter, but becomes outwardly broader 

 and more swollen, so as to terminate in a knob-like rounded extremity (PL XXV. fig. 4). 



The parenchyma of the tube-like stalk contains, just as in Caulophacus latus, some- 

 what rough, rod-like diacts, which are rounded at both extremities. They are greatly 

 increased at the expense of the hexacts, which have disappeared, and are almost all 

 approximately parallel to the long axis of the stalk. It is only in the inferior portion of 

 the stalk that the diacts ai'e firmly united by means of synapticula. 



The pentact-hypodermalia of the dermal skeleton are roughened only on the extremity 

 of the proximal, and of the four transverse rays. 



The autodermalia of the stalk are pentact pinuli in which the proximal ray is 

 atrophied to the size of a small tubercle, while the freely projecting distal, on the 

 contrary, has become a squamous pronged ray, 075 mm. or more in length. This 

 increases in breadth outwardly, and, like the autogastralia of the discoid upper surface 

 terminates in a knob-like thickening. 



