Vi (9M 



Òn a New Species of Deep-Sea Polychaeta 



(Pant hai is Mitsukurii.) 



BY 



Akira Izuka, Rigakushi. 



Assistant Professor of Zoology, Imperial University, Tokyo. 



With Plate I. 



During the past four years, four interesting annelid specimens of a 

 large size, apparently representing an undescribed species of the genus 

 Panthalis in the family Aphroditida;, have been placed at my disposal 

 for examination and description. I beg to call the species Panthalis 

 jMitsuhirii in dedication to the gentleman whose name is borrowed for 

 the specific appellation. 



All the specimens hitherto obtained arc more or less incomplete 

 in that they lack the posterior parts, though always preserving the 

 head end. They come from a considerable depth in the Sagami Bay 

 and the adjacent waters. Particulars about each specimen are as 

 follows : 



Specimen A. — Acquired by exchange by the Science College from 

 Mr. Komeva.ma. Locality, Sagami Bay. Depth unknown. It mea- 

 sures 310 mm. in length, having 128 segments. The maximum breadth, 

 including the parapodia and seta;, in the region of about the 20th 

 segment, is 32 mm., and in exclusion of the parapodia, 22 mm. The 

 last segment at the torn posterior end is 25 mm. broad including the 

 parapodia and seta;, and 14 mm. in exclusion of these. The maximum 

 thickness is 18 mm. 



