THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTOUY. 



[FOURTH SERIES.] 

 No. 87. MARCH 1875. 



XX. — On Pelagonemertes Rollestoni. By H. N. Moseley, 

 Naturalist on board H.M.S. 'Challenger.' 



[Plate XV. B.] 



This remarkable form was found in the trawl, together with 

 a number oi" deep-sea animals, from 1800 fathoms, near the 

 southern verge of the South-Australian current, lat. 50° 1' S., 

 long. 123° 4' E., March 7, 1874. Its appearance at once pro- 

 nounced it a pelagic animal, the body being gelatinous and 

 transparent, as in Salpa, with the exception of the alimentary 

 canal, which stood out in relief, being of a deep burnt-sienna 

 colour {as is the nucleus in many Salpce) , and the region of the 

 sheath of the proboscis, which was less transparent than the 

 remainder of the body. The animal was living when obtained, 

 and when placed in fresh sea- water gave evidence of life by a 

 feeble irregular peristaltic contraction of the external muscular 

 tunic, which increased on irritation ; the proboscis was also 

 protruded and retracted several times. 



The animal was about 4 centims. long and 2 broad, and 

 5 millims. in thickness. Hence its dimensions, and especially 

 its thickness, render it unfavourable for a perfect examination 

 of its structure under the microscope whilst in the entire con- 

 dition. As only one specimen was procured, and as this was 

 believed to be unique, no dissection was resorted to, excepting 

 the removal of a small portion of the epidermis and external 

 muscular tunic for microscopic examination. Hence the 

 investigation of the structure of this Nemertine necessarily 



Ann. d'Mag. X. Hist. Scr. 4. Vol. xv. 12 



