188 AMT. ".— I. IJliMA: IIEXACTINELLIDA, IV. 



sha]3ecl. They are on the whole slightly smaller and more slender- 

 rayed than in those in or near the endosome ; besides, the terminals 

 are always more or less distinctly rough (PL XIV., fig. 17). The 

 roughness is in many cases plainly attributable to minute and inward- 

 ly directed barbs, especially distinct in the basal parts of terminals. 



Hemihexactinose forms of the oxyhexaster most commonly 

 show one or two uniterminal principals, the rest of the principals 

 being each in possession of two terminals as is usually the case. 

 The terminals are nearly straight and more or less rough-surfaced. 



Hexactinose oxyhexasters (PL XIII. , fig. 7) have likewise 

 rough rays which are however frequently not quite straight but 

 somewhat wavy. They are quite numerous in the choanosome, a 

 fact which may perhaps be regarded as constituting one of the 

 peculiarities of the species. 



Occasionally I have met with interesting exceptional forms 

 of the oxyhexaster, in which the hexactinose character is still 

 further modified into the pentactinose and even the stauractinose 

 by a complete suj^pression of the terminals on one or more of 

 the principals. The principals, thus deprived of their terminals, 

 remain in their position as smoothly rounded off prominences 

 which leave no room to doubt that the terminals have not been 

 lost by mechanical breakage Ijut were undeveloped from the first. 

 The above, evidently abnormal, forms were not noticed in the 

 second specimen. In this, on the other hand, I have not infre- 

 quently met with the small rudimentary-looking spicules shown 

 in PL XIV., fig. 22. These contain a small axial cross of 

 filaments and there can be no doubt about their being oxyhexasters 

 with terminals but little developed, though it is difficult to 

 decide whether we have to do with early developmental stages or 

 with abnormal appearances. 



