26 THE SPONGES. 



The micro-oxyhexacts agree with those of 11. hianchoratum. The 



dermal pinnies also resemble those of the latter species, differing only in 

 that the upper spines on the distal ray are somewhat longer, the ray thus 

 appearing more bushy. There are two types of macramphidisc essen- 

 tially like those of //. hianchoratum. In the case of the larger type, the 

 total length reaches 510 fx ; the shaft bears 3 or 4 scattered sharp micro- 

 tubercles ; the depth of the umbel is ^ the total length ; spicule fairly 

 abundant. In the case of the shorter type, the umbel rays commonly reach 

 equator of spicule, often slightly interdigitating ; total length reaching 

 255 /a; larger sizes of the spicule truncated at the poles and with flattened 



sides, as in Fig. 1, Plate 2. The smaller amphidiscs, 24-70 ^a long, 



do not differ from those of H. hianchoratimi. Acanthophorae are pres- 

 ent and include stauractines and diactines. Spicules are spinose only at 

 the ends of the rays ; ends often rounded and enlarged, also pointed. The 

 spiculation indicates that the fragment belongs to H. hianclmratwn, perhaps 

 representing a local variety of this species. 



Hyalonema 2. 



Station SJflJf, a fragment from the peripheral part of the sponge includ- 

 ing both dermal and gastral surfaces, and about 50 mm. wide with a 

 greatest thickness of 20 mm. On the gastral surface are the apertures of 

 several canals about 7 mm. wide. 



The micro-oxyhexacts agree with those of H. hianchoratum, but forms 



with straight rays predominate. The pinules of the dermal and gastral 



surfaces agree closely with those of H. hianchoratum. There are two 



types of macramphidisc, shown in Figs. 13 and 16, Plate 2, which differ 

 only in minute details from the macramphidiscs of H. hianchoratum. In 

 the larger type, Fig. 13, the total length is 250-320 /x ; shaft smooth or 

 with a few scattered sharp tubercles and often with 4 or 6 protuberances 

 at the middle. A typical spicule measures : total length, 280 /x ; depth of 

 umbel, 90 /x ; width of umbel, 130 /a. In the smaller type, Fig. 16, the 

 total length is 100-150 /x ; rays of opposite umbels often shghtly inter- 

 digitating at the equator of spicule. The umbels are never conspicuously 

 truncated and flattened as in many of the spicules of H. hianchoratum 

 (Fig. 1, Plate 2). A typical spicule measures : total length, 144 yu, ; depth 

 of umbel, 70 />t; width of umbel, 100 /z. 



In addition, amphidiscs of the type shown in Figs. 14 and 15, Plate 2, 

 are fairly abundant. The total length is 150-180 /x. ; umbel depth varying 



