OX CTEN POHORES OF THE NEIGHBOURHOOD OF MISAKI. 47 1 



tried to swallow an Ocyropsis, several times larger in size. It was 

 further observed that the animal sometimes turned itself inside out, to 

 return to the normal condition after some time. 



Remark. — B. mitrata, first described by Moser under the name 

 of Pandora mitrata, may be distinguishable from all allied species by 

 the two sets of ribs differing considerably in length, by the characteris- 

 tic distribution of branches of meridional canals, and by the presence 

 of a network of canals in the oral parts of pharyngeal wall. The genus 

 Pandora, first established by ESCHSCHOLTZ, was later merged into 

 Bero'è by Chun, and has recently been reinstated by MOSER. Accord- 

 ing to the last-named authoress, the genus comes very near to Bero'è, 

 but is distinguishable from it chiefly by the shortness of ribs and by 

 the subpharyngeal ribs being longer than the subtentacular ribs. Such 

 a condition of the ribs, however, is very commonly presented by various 

 species of Beroë, especially in their young stages, as for instance, by 

 half-grown individuals of B. campana. In the species just mentioned, I 

 may say, on the basis of my own observation, that the shortness and 

 unequal ness of ribs in length is a normal character in the young. The 

 same apparently holds true for B. forskälii also. MAYER has likewise 

 pointed out (191 2, p. 54) that the same condition is very often met 

 with in the young of B. ovata. Now Pandora was made to comprise 

 three species besides two doubtful ones, all of which have been described 

 from animals of a small size {P. flemmigii, 3-25 mm. ; P. pandorina, 

 2-6 mm. ; P. mitrata, 5-28 mm.). From this it may be assumed that 

 all the forms stand represented by young individuals with ribs of 

 unequal length, which character later diminishes considerably or dis- 

 appears altogether. If that be so, Pandora would lose almost all 

 grounds for being held separate from Beroë. 



