18 



AKT. 2. — H. MATSUMOTO 



within the disk and at the 

 base of the arms, where the 

 fusion is complete. Each 

 vertebra has at its middle 

 part a longitudinally fusiform 

 pore, which becomes larger 

 and longer in the more distal 

 part of the arm and finally 

 divides the vertebra into halves. 

 Dorsal arm plates small, 

 oval, thin, transparent, longer 

 than wide, wider within than 

 without, separated fi'om each 

 other ; they lie over the distal 

 parts of the vertebrœ of the 

 Fig. 2. OpUoinjaius gotoi. a. From above. x7. corresponding arm joiuts, and 



h. From below. x7. c. Side view of three arm 



joints near disk. x7. d. Dorsal view of two arm bcCOmO Very Small and dclicato 



joints near the extremity, x 14. e. Ventral view ■ iii j. •> c i^ 



„. ... , , ,. , .^ towards the extremity of the 



of two arm joints somewhat near the extremity. «^ 



xi6. /. Dorsal view of the vertebra of the arm. Lateral arm plates slight - 



fourth free arm joint, x 14. g. Dorsal view of 



the vertebra of the tenth free arm joint. X U. ly flarcd, SUCCCSSlve plateS 



not in contact with each 

 other, but separated by a naked space, which is widened up- 

 wards and continued into a large naked space bounded by the 

 dorsal and lateral arm plates and the vertebra. First ventral arm 

 plate not very small, quadrangular, with strongly curved outer 

 edge, much wider without than within. Those beyond nearly 

 rhomboidal in outline, with a conspicuous notch at the outer 

 end and a half pore for the tentacle at each lateral angle ; 

 much longer than wide, being widest at the outer ends of the 

 tentacle pores ; successive plates not in contact with each other, 



