150 Notice on Balantium. [Feb. 



X. — Notice on Balantium, a genns of the Pteropodous Mollusca ; icith 

 the characters of a new species inhabiting the Southern Indian Ocean. 

 ByW.H. Benson, Esq. B. C. S. 



In Vol. iv. J. A. S., page 176, I enumerated the genera of Ptero- 

 poda met with in my voyage from England, and noticed, under No. 

 11, a new perforate genus a'lied to Cleodora, which I marked as very 

 rare, in consequence of the specimen which fell to my net having 

 been the only one seen during the passage. 



On looking over the plates of Lamarckian genera of Testacea given 

 in the old series of the London Quarterly Journal of Science, Vol. XV. 

 I met wiith a figure, No. 107, Plate VII., which bore a very near re- 

 semblance to the shell from which I intended to draw the characters of 

 a new genus ; and on reference to the letter-press, page 220, I found 

 a note which had theretofore escaped my notice, containing the 

 characters of the genus Balantium, which the anonymous translator 

 proposed to establish in order to receive a shell taken by Mr. C ranch, 

 in Captain Tuckey's expedition to the Congo, and preserved with 

 another shell, apparently of the same genus, in the British Museum. 

 The writer assigned the shell provisionally to the family of Hyalccana, 

 merely from the strong analogy which the substance of the shell bore 

 to that of Hyalcea, until an opportunity should occur of obtaining 

 more accurate information regarding a species so interesting. That 

 opportunity has partly occurred to me, and I am enabled, bv the 

 discovery of a second allied species, to confirm, from an inspection of 

 the animal, the correctness of the writer's conjecture regarding the 

 location of the genus in the order Pteropoda. The following is the 

 description of Balantium recurvum, as given in Brande's Journal. 



" Shell transparent, very thin and fragile, hyaline, corneous, hasti- 

 form ; apex recurved ; open at both ends ; superior aperture dilated, 

 sharp-edged ; inferior round, very minute ; sides acute ; superior disk 

 undulated; inferior rounded; numerous transverse grooves on both 

 sides." 



The new species differs from the description in having no re- 

 curved termination to the shell, or at least the bend is so incon- 

 spicuous, as to be of no value as a character ; the terminal aperture 

 is also larger in proportion, being, in my specimen, nearly 0.05 of an 

 inch in diameter. It has on one face three radiating longitudinal 

 ribs, (one central and broadest, and two lateral.) The lateral margins 

 are more regular than in B. recurvum, are destitute of the grooves 

 which cross the shell transversely, and are provided with a groove 

 running the whole length of thejr truncated edge, whence it happens 



