ABT. 12 HEXACTINELLID SPONGES OKADA 91 



Remarks. — This new species resembles A. ijimai in essential mode 

 of spiculation but differs from it in the shapes of the dermal and 

 gastral hexactins and the outer feature of the parenchymal oxyhex- 

 aster. 



BATHYDORUS UNDETERMINED 



Here are mentioned three specimens that I have studied but which 

 I prefer to leave unnamed, I provisionally place them in the genus 

 Bathydorus. One of them is very small and probably a young 

 specimen in which the cliaracters have not been fully developed. 

 The other two are broken into several fragments, which were pre- 

 served in a badly macerated condition. 



BATHYDORUS, a species 



Pi/ATE 6, Figure 2 



This is a little specimen collected at Station 4917, about 90 miles 

 west by southwest of Kagoshima Gulf at a depth of 361 fathoms, 

 together with SericolojyJius reflexus (Ijima). The body is barrel- 

 like in shape, measures 14.5 mm high and 7 mm broad, and is at- 

 tached to a mass of pebbles. From the body proper arise fine prostal 

 needles of a considerable length, mostl}'' directed obliquely upward 

 and outward. The dermal surface is smooth. The parenchymalia 

 are chiefly diactins less than 12/a thick. Nearly all the surface is 

 smooth ; occasionally it is rough at both ends. 



The dermalia are predominantly stauractins, the plane of which 

 is usually slightly convex on the outer side. The length of their 

 rays varies from Goyu. to 80/x. They are 4/* in breadth at their base. 



The relatively strong and slightly tapering rays are entirely 

 rough with distinct but sparse microtubercles. The atrophied rays 

 are entirely absent in the present spicule. 



The gastralia are hexactins found in dense but irregular distribu- 

 tion. They do not form a regular latticework. The surfaces of the 

 rays are much more prominently microspined. The paratangentials 

 usually measure 70/x to 80/a in length; the distal ray is shortest of 

 all, while the proximal is 120|u, to ISO/u long, tapering toward the 

 pointed and curved ends. 



The hypodermalia are moderately large pentactins, with their 

 rays gradually tapered toward the conically pointed ends. The 

 paratangentials measure SGO^ti to 400|U, in length and IS^u, to 16|a in 

 breadth near the spicular center. The proximal fifth ray is always 

 longer than the paratangential in the same spicule and at times is 

 nearly twice as long. Seen in surface-view preparations, the 

 paratangential crosses are situated for the most part without any 

 regular or " mutual " arrangement, though at places they approach 

 the formation of a quadrate-meshed latticework. 



