AKT. 12 HEXACTINELLID SPONGES — OKADA 93 



The smaller parenchymalia down to comitalia only lOjx in thick- 

 ness are of the usual description. The tips are acuminate, rounded, 

 conical, or mucronate; infrequently they are swollen to a clublike 

 or even a bulbous shape. 



Hypodermal pentactins are well developed and show essentially 

 the same characters and arrangements as in common members of 

 Staurocalyptus, being isolated or sometimes standing out in small 

 loose groups. Paratangentials do not exceed 4 mm in length; the 

 shaft is longer, measuring up to 7 mm. They are either paratropal 

 or almost regularly cruciate. The surfaces of all rays are quite 

 smooth except at the ends, the surface of which is roughened by 

 densely distributed microtubercles. All the rays are gradually at- 

 tenuated toward the conically or sharply pointed ends. 



The dermalia are rather thick-rayed pentactins, with the unpaired 

 ray directed proximally. Their paratangential rays are in a plane 

 slightly arched on the inside. Occasionally stauractins are found, 

 intermingled here and there with the former spicules. The paratan- 

 gentials, from the central point, measure dO/x to 100/x, while the 

 ]:)roximal unpaired rays are 100/x to 110/x, in length. The thickness 

 at base averages 12/x. The rays are slightly narrowed outward; 

 the tip is rounded or somewhat conically pointed. Their surface 

 is thickly beset nearly all over with distinct microspines, which are 

 much more pronounced at the ends. In the stauractins, the rays are 

 somewhat longer, 120/x to 135/i. long, also in a plane, slightly arched 

 on the inside. The aborted rays of both spicules are at most repre- 

 sented by vestigial bosses. 



The gastralia are strong and long hexactijtis, for the most part 

 fulh' twice as long as the dermalia. The rays are somewhat more 

 tapering toward their ends; the microspines or microtubercles on the 

 surface are in like manner moderately developed. Length of 

 rays : Paratangentials, 130|U, to 180/a ; distal ray, 130/i, to IGOja ; proxi- 

 mal, ISOfi to 210|u. The raj^s at the base are somewhat slender, aver- 

 aging Six thick. 



The oxyhexasters consist of three kinds, namely, normal oxyhex- 

 aster, hemihexactinic, and hexactinic. The normally developed oxy- 

 hexaster occurs less abundantly in all parts, but it is especially plenti- 

 ful near the ectosome. Its diameter is 90/x to 135ju,. There is no 

 appreciable difference in appearance between those in the periphery 

 and others situated more deeply in the wall. From each exceedingly 

 short principal two or three rather thin, obscurely rough-surfaced, 

 and nearly straight terminals diverge. Occasionally the principals 

 appear distinctly circular-knoblike in shape, measuring lOfi in size. 

 Oftener the oxyhexasters seem to be hemihexactinic and occasionally 

 quite hexactinic forms. In the hemihexactins, the diameter meas- 



