AKT. 12 HEXACTIISrELLID SPONGES — OKADA 65 



developed, measuring 24ju, to 28/* in length, and are four, sometimes 

 six, in number. They differ somewhat from those of the other speci- 

 mens in having a strongly rounded apex at the head; not pointed 

 as a gothic arch as in the other specimens from same locality. 



In specimen B, 2, the diameter of the parietal pore is usually 1 

 mm and seems not to exceed this size. The parietal ledges are 

 prominently developed, frequently measuring 5 mm in height, espe- 

 cially those of the "oscular margin close to the outer margin of the 

 sieve plate, which approach 6 mm in height. The wall of the body 

 is also thick, as in specimen B, 1, measuring 4 mm at the middle of 

 the body, and becoming gradually thinner toward the upper and 

 lower ends, measuring 2.3 mm. 



Splculatlon. — The hexactin of the dermalia is not so large as that 

 of specimen B, 1, usually having the blade ray 830/a to 1,370|U, long. 

 The jjaratangential rays are proportionalh'' very short, measuring 

 66/A to 121/j, in length. 



Form 5 of the floricome in specimen B, 1, is probably not present 

 in this specimen. The basalia do not differ from those of the type 

 specimens, except in being slightly robuster and in having a per- 

 ceptibh' thicker shaft. The anchor teeth, of which there are five to 

 eight in each head (usually six or seven) are strong and about CO/i 

 long. The distance from tip to tip of any two oppositely situated 

 anchor teeth is 80/x to 88fi. The shaft is 24ju, thick close to its origin 

 from the head. 



Specimen B, 3, is the smallest sjDecimen obtained from the same lo- 

 cation. It does not have such prominent parietal ledges as specimens 

 B, 1 and 2. They measure 2 to 3 mm in height, and have sharp edges. 



Sijnculation. — Among the basalia, there is occasionally found a 

 much smaller form of anchor-toothed spicule than in the typical 

 form. The apex of its head is rather pointed as in a Gothic arch. 

 The anchor teeth vary in length from 12/«, to 24/*, and their numbers 

 are constantly 4. The distance from tip to tip of any two opposed 

 anchor teeth is 32/i to 56/i. The shaft close to the head is 8/* to 12/x 

 thick. The spines on the shaft are not so conspicuous as those of the 

 typical form and become more degenerate in number and length. 

 Especially in the smallest one (basalia?), the spines are very short 

 and are projected at wide intervals. These forms seem to be inter- 

 mediate and probably grade over into the common anchor-toothed 

 basalia and the pentactin basalia of these varieties. 



An abnormality, like that occurring in the specimen from station 

 4948, is shown by three short tubercular spines projected sideways 

 118040—32 5 



