NO. 2247. SPONGES FROM NORTHWESTERN PACIFIC— HOZAWA. 529 



assemblage of recticulating ascon tubes. It is of a flattened oval 

 shape, broadest at the upper end and narrowed toward the lower 

 end, which forms a short stalk for attachment. It is apparently 

 devoid of either an osculum or a pseudosculum. Total length about 

 15 mm. ; greatest breadth about 10* mm. The thickness is about 

 5 mm. as measured in the thickest part. The entire outer surface 

 of the sponge seems to be covered with a finely folded continuous 

 membrane. The recticulation of ascon tubes is rather loose. Gray- 

 ish white in alcohol. Soft and delicate in texture. 



Structure. — The bad state of preservation of the specimen made it 

 difficult to ascertain the fine internal structure. However, it is prob- 

 able that the ascon tubes have no papillae on the inner surface. 



The skeleton is composed of triradiates and quadriradiates, ar- 

 ranged in a single layer in the wall of ascon tubes. Some of the 

 former are provided with a small knob representing the rudimentary 

 apical ray. The latter occur relatively sparsely and mixed together 

 with the triradiates; their apical rays project into the gastral cavity. 

 There is no conspicuous difference in size between the dermal and the 

 more deeply situated spicules. 



Spicules. — Triradiates regular, with rays straight, usually some- 

 what bluntly and sometimes sharply pointed, rather slender, 50-140/* 

 long and 6-12/x thick at base. 



Quadriradiates of the same shape and size as the triradiates, but 

 with a short, slender, straight, and sharply pointed apical ray. In 

 an example of the spicule, the apical ray measured 30/i long and 2/i 

 thick at base. 



Localities. — Canary Islands (Michlucho-Maclay, Haeckel) ; Cape 

 Verde Islands (Thacker) ; Mauritius (Schuffner) ; Minorca (Laks- 

 chewitsch) ; Spitzbergen, Arctic Ocean (Breitfuss) ; off the north 

 point of Copper Island, Comandorski Islands (Station 4789, 56 

 fathoms) . * 



3. SYCON SIMUSHIRENSIS, new species. 



Plate 84, fig. 6. 



This new species is based on a single specimen in the collection 

 (Cat. No. 9170 U.S.N.M.). It is a small solitary mdividual (pi. 84, 

 fig. 6) of a slightly laterally compressed tubular shape, narrowed at 

 base, which is torn off. The osculum at the upper end is in a col- 

 lapsed state. Length about 9 mm.; the greatest breadth about 2 

 mm.; thickness of wall not over 0.4 mm. To the naked eye both 

 dermal and gastral surfaces appear nearly smooth. Color grayish 

 white in alcohol. Texture moderately firm. 



Structure. — The canal system is of the syconoid type. The flagel- 

 late chambers are arranged radially around the rather wide gastral 

 3343— 19— Proc.N.M.vol.54 35 



