ART. 12 



HEXACTINELLID SPONGES — OKADA 



73 



Oxyhexasters are represented by normal hemihexactinic and hexac- 

 tinic forms. The first are abundant and exhibit a distinct knoblike 

 center and very short principals. 



The distinct parench^anal diactins which become very much at- 

 tenuated toward both ends seem not to be represented in the smaller 

 specimen. Instead are found large diactins, which measure 5 mm to 

 6 mm long and Soju to ISO^u, broad. 



The basidictyonal plate is not completely formed, being repre- 

 sented by large individual or compound stauractins with ends bi- 

 furcated or multifurcated, connecting with those of other approach- 

 ing stauractins. The surface is nearly smooth, except near the ends, 

 which have scattered microspines. . 



Genus AULOSACCUS Ijima, 1896 



This genus was originally established by Ijima because it differs 

 from Scyphidium and Rossella in having no pentactinic hypoder- 

 malia, though otherwise it shows great affinity to both genera. If 

 certain si^ecies of AuJosaccus described by him were only provided 

 with pentactinic hypodermalia, there would have been no hesitation 

 in including it in Scyphidium at that time. But in the various 

 specimens in the collection before me, I have always found a pentac- 

 tinic hypodermalia. The spicule in question easily drops from the 

 dermal surface of the sponge and is not observed in poorly preserved 

 specimens. Although Ijima mentioned the absence of hj^podermal 

 pentactins as the most important character of the genus, I maintain 

 that it may be regarded as distinct from the genera Rossella and 

 Scyphidium in having the macrodiscohexaster as well as the hypo- 

 dermal pentactin. 



AULOSACCUS FISSURATUS, new species 



Figure S 



Both of the complete specimens are very similar in appearance, 

 being large and vaselike in shape, attached by a somewhat narrowed 

 base, and having at the broad upper end a large circular osculum. 

 The larger specimen, which I make the type of the species (U.S.N.M. 

 No. 22114), is nearly 175 mm long and 100 mm broad at the broadest 

 part. The circular osculum measures 80 mm in diameter. 



Table 19. — Record of specimens of Aulosaccus fissuratus 



