406 Mr. W. H. Benson on Ianthina, Bolten. 



(agreeing rather with the shell figured in the Voyage of the 

 ' Samarang ' than with the very different form assigned to the 

 species in pi. 2. f. 9. of the f Iconica'), first occurred in company 

 with /. nitens, and continued at intervals as far as 35° S. lat. 

 and 74° E. long., generally with /. exigua. I had not the good 

 fortune to catch such large specimens of this species as were 

 taken by one or two of my companions. 



About midway between Sierra Leone and Paraiba, 3° north of 

 the line, and in about 24° of west longitude, we sailed during 

 half an hour, on the 10th of October, through a space occupied 

 by a fine species, the more depressed forms of which appear to be 

 Lamarck's/, fragilis (not I. fragilis, Reeve) . The spire is variously 

 elevated, until in one specimen it attains the exact figure of 

 Reeve's /. affinis, considered by Mbrch to be merely a variety 

 of /. fragilis. Nine specimens were captured, of which four fell 

 to my net. Several fine ones were missed. This species was 

 not again seen until, in the Bay of Bengal, to the north-east of 

 the Andamans, I took in my casting-net eight specimens of a 

 variety in an immature state. Trochus Ianthinus, the original 

 species of Chemnitz, which has a similar elevated spire, is as- 

 signed to Tranquebar^ on the Coromandel coast of the same bay. 



The next form obtained was a beautiful little purple /. umbi- 

 licata, D'Orb., the finest specimens exhibiting an incision in the 

 outer lip nearly as deep as that to which /. bifida, Nuttall, owes 

 its name. From its locality (about a degree north of the line), 

 until we had attained 14° of north latitude in the Bay of Bengal, 

 it was not observed. I then took a single specimen of a large 

 solid variety ; and some minute examples accompanied /. exigua 

 to the head of the bay. 



As we approached the Tristan d'Acunha group, in the Southern 

 Atlantic, we sailed for several days through a tract, from 30° S. 

 lat. and 18° W. long, to 33° S. and 10° W., inhabited by a 

 fine white and violet-coloured Ianthina pallida, Harvey, in com- 

 pany with a large variety of /. exigua. On the last day of its 

 appearance we passed specimens of a very large size ; but the 

 rate (8 knots) at which the ship was sailing through a strong 

 swell, caused the loss of my casting and towing nets in the 

 attempts made to procure them. On the following day, when 

 the weather had become favourable, not a single specimen of /. 

 pallida was visible ; and it did not again appear until we had 

 reached a point to the north-east of the Isles of St. Paul and 

 Amsterdam, where a small pale variety was accompanied by the 

 Ianthina next to be noticed : the species then disappeared for 

 the rest of the voyage. 



From the 1st to the 5th of December, between 33° and 30° 

 south latitude and 81° and 83° east longitude, the ' Malcolm' 



