no. 2073. HOLOTHURIANS FROM 'NORTHWEST PACIFIC— OH SHI MA. 259 



row along the odd ambulacrum, in a single row in each ventrolateral 

 ambulacrum. In the largest specimen there are 34 pedicels in the odd 

 ambulacrum, 20 and 22 respectively in the paired ambulacra. In 

 each dorsal ambulacrum there are at most 7 knoblike pedicels in a 

 single row; a few similar knobs are present at the anterior ends of 

 the ventral ambulacra. In young specimens the dorsal ambulacra 

 are almost destitute of appendages. Interambulacra are completely 

 naked. Deposits are of a characteristic form, being delicate, smooth 

 rods with both ends branched once or twice dichotomously (pi. 10, 

 figs. 18a, c). Their length varies 45-180/*, with a mean of 94/*. 

 These are by no means crowded but are quite sparse, especially in 

 dorsum. Between them there are deposits of another form, simple 

 rods with a joint at the middle (fig. 186), with the average length 

 of 63,«, varying 25-107 '/*. Probably these are early stages of the 

 above-mentioned branched bodies. Single deposits heavy at the 

 posterior end but no anal teeth can be found, those of introvert not 

 distinguishable from those of general perisome. In pedicels and 

 papillae deposits are numerous, much branched, sometimes nearly 

 forming a perforated plate. End plates of pedicels well developed, 

 measuring 405-67 0/x in diameter. Supporting bodies of tentacles 

 are irregular rods and large, curved, perforated plates. Calcareous 

 ring quite weakly calcified, without posterior prolongations. Retrac- 

 tors thin and threadlike, inserted to body wall about one-fourth the 

 body length from the anterior end. Polian vesicle and stone-canal 

 single. Respiratory trees two, rudimentary, measuring only 6 mm. 

 in length, with a few finger-shaped branches. Genital tubes un- 

 branched, about 20 mm. long and 1 mm. thick, in two tufts of a few 

 tubes each. Ovarian ova measure 0.5-0.55 mm. in diameter. Geni- 

 tal papilla situated between the mid-dorsal tentacles. 



In all females above 10 mm. in length, a pair of brood pouches are 

 present in the ventral interambulacra, about 3-4 mm. behind the ten- 

 tacular crown. When filled with young these pouches occupy almost 

 the whole body cavity; thus, in a specimen 16 mm. long, the right 

 pouch measured 11 mm. by 7 mm. and the left one 8 mm. by 6.5 mm. 

 The wall of the pouch is very thin and transparent, and without 

 deposits. So far as my examinations extended, the young were all 

 in the same stage of development. In the specimen just referred to, 

 there were 12 young in the right pouch and 7 in the other. In an 

 extreme case 16 young were contained in a single pouch. 



The size of the young observed by me varied in length between 2 

 and 7 mm. with a mean of 5 mm., and in diameter between 1 and 4 

 mm. with a mean of 3 mm. Some of their characteristics may be 

 given. Body wall very thin and transparent, so that the internal 

 organs are easily visible from ouside. Around the mouth, which is 

 already open, there are 10 quite short tentacles with a few branches. 



