288 MR. H. ADAMS ON NEW MASCARENE SHELLS. [May 14, 



a similar phenomenon will, I imagine, be eventually proved to occur 

 amongst fishes. 



The cavity in the head cannot affect this aestivation, because it is 

 not only the hollow-headed Acanthopterygians which thus reappear 

 after rain, but also Cyprinidse and others, which, if this cavity were 

 necessary for this purpose, must die when the water dried up, and 

 would thus soon become extinct in many places. As I have every 

 reason to hope that some of the specimens of Ophiocephalidse which 

 I had the pleasure of despatching to Europe by the mail of March 

 may arrive safely, I append a few observations respecting their 

 habits. I have kept some of these fish for some time in aquaria 

 at Madras. When first in confinement they were very wild and 

 frightened ; but they gradually became very tame, and fed from the 

 hand without fear. The aquarium in which they are kept should 

 always have plenty of clean sand at the bottom, and no rockwork, as 

 they are apt to thrust against it violently with their noses ; and in 

 several instances their jaws were thus denuded of skin and their 

 heads of scales, producing great irritation, which caused the cessa- 

 tion of the secretion of healthy mucus, and frequently resulted in 

 death. They require very little water, and may be seen lying on 

 the sand, occasionally lazily raising their heads, if the water is 

 shallow, and taking in air. They are fond of grass and aquatic 

 plants in the aquarium, and the small specimens then lie amongst 

 them on the surface of the water, thus saving themselves the trouble 

 of rising from the sand for air. But as they are continually biting 

 at the grass, the water becomes very dirty ; and it was therefore dis- 

 continued, and the fish did quite as well without it. If the water is 

 dirty they scarcely appear to move their gills, but about every two 

 or three minutes ascend to the top, emit their bubble, and descend. 

 Their habits are dirty ; and the water is constantly vitiated by the 

 large amount of mucus they exude from their bodies, as well as by 

 the rejection of their food in small shreds after it has been swal- 

 lowed. Fresh water should be given them every day, as otherwise 

 it becomes foul and offensive. When it is changed they become 

 wildly excited and rush about, probably in the same manner as 

 when aroused suddenly from their "summer sleep." 



6. Descriptions of some new Species of Shells collected by 

 Geoffrey Nevill, Esq., at Mauritius, the Isle of Bourbon, 

 and the Seychelles. By Henry Adams, F.L.S. 



(Plate XXVIII.) 



CoNus (Chelyconus) borbonicus, H. Ad. (PI. XXVIII. 



C. testa convexo-conicn, angusta, Icevigata, solidiuscula, antice spi- 

 nditer lirata, rosco-lutca, fascia albida obscura in tnedio cincta. 



