Benham. — On a Large Pterotrachmd. 245 



Fig. 1. Tokea maorica. 



Fig. 2. Tokea decipiens. 



Fig. 3. Ehododrilus similis. 



Fig. 4. Rhododrilus similis. Ventral view of the segments 19-21, show- 

 ing the character of the tubercula pubertatis as seen under a 

 dissecting-lens. 



Fig. 5. Rh. similis. The end of a penial chaeta ; X 480. 



Fig. 6. The same, much enlarged, showing the pittings on the surface. 



Fig. 7. Rh. similis. A spermatheca. d. diverticulum. 



Fig. 8. Tokea maorica. Spermatheca. 



Fig. 9. T. maorica. Proximal end of the prostate, showing relative size 

 of the duct. 



Fig. 10. Dinodrilus suteri. A spermatheca. 



Art. XXVII. — On a Large Pterotrachceid from the Pacific Ocean. 



By W. B. Benham, D.Sc, M.A., F.Z.S., Professor of 

 Biology in the University of Otago. 

 [Read before the Otago Institute, 10th October. 1905.] 

 Plate XLIII. 

 Hitherto only a single species of the pelagic group of Gas- 

 tropods, the Heteropoda, has been recorded from the seas that 

 wash our coasts. This is Carinaria australis* Q. and Gr., which 

 was obtained in 1827, during the voyage of the " Astrolabe," 

 between Australia and New Zealand. We may now add Firola 

 (Pterotrachea) coronata, Forskal, to our marine fauna. 



The specimen upon which this identification rests was washed 

 ashore during January, 1905, at Long Beach, a few miles north 

 of the Otago Harbour. Luckily for zoology, it was observed 

 Ling on the sandy shore and secured by Mr. W. Fels, of Dunedin, 

 who transmitted it to me at the Museum. Unfortunately, it 

 had been somewhat damaged by the tossing of the surf and 

 by rolling on the sandy beach ; thus the epidermis and under- 

 lying tissue was in great part rubbed off. The posterior end 

 (metapodium) had been broken away behind the visceral hump. 

 The visceral mass itself was a good deal damaged — only three 

 or four gill- filaments remained of the gill — and part of the male 

 copulatory organ was broken away. The ventral fin (or meso- 

 podium) is also a good deal damaged, at least half of it being 

 absent ; but I believe that so much as remains suffices to 

 establish the specific identity with F. coronata. 



An examination of the literature available showed me that 

 the specimen is much larger than the majority of species of 

 Pterotrachea (Firola), though P. adamastor, Lesson, from the 



* Quoy and Gaimard, Voy. de 1' Astrolabe, vol. ii, p. 394. 



