212 Mr. F. P. Marrat on some new Species o/'Oliva. 



amongst other instances, to a great number of Dipterous genera 

 the larvse of which wallow in the excess of their food, and 

 mentions that, out of 403 species of these Diptera, Meigen knew 

 only the females of 255. But these examples cannot be 

 adduced as in the least in favour of Landois's theory ; for 

 Meigen, in his well-known ^ Systematische Beschreibung der 

 europaischen zweiflugeligen Insekten,' very frequently, by his 

 own admission, had only a single female and also very often 

 only a single male in his hands as the type of the descriptions 

 of his species. Such scanty material as this is certainly 

 insufficient to prove the predominance of one sex over the 

 other. 



XXII.— O/i some new Species o/*01iva. 

 By F. P. Marrat. 



In selecting the following shells and describing them as new 

 species, I have been guided principally by prominent features 

 in each case, that, in my opinion, warrant the selection and 

 publication. 



OUva lignaria^ Marrat, is very remarkable : at one time I 

 supposed it might be a variety of 0. injlata^ Lam. ; at another 

 its resemblance to 0. maura^ Lam., appeared to be considera- 

 ble ; and at a third it was, until compared, thought to be a 

 variety of 0. irisansj Lam. It may prove to be a variety of any 

 one of these three shells when specimens are obtained show- 

 ing the gradual variation ; but at present a shell possessing 

 such connecting characters is still to be brought under notice. 



0. sabulosa, Marrat. — The specimens of this shell are de- 

 scribed as having red-brown markings. I think, in most if 

 not in all cases, the original colour has been dark brown, and 

 that bleaching in the sun has produced the red-brown colour, 

 notwithstanding one of the shells is brilliantly polished and 

 possesses all the appearance of a dredged shell. 



I am much surprised that a shell of rather common occur- 

 rence and so decidedly distinct as 0. angustataj Marrat, should 

 have remained so long unnoticed by conchologists. Years 

 ago its form was familiar to me among the shells imported in 

 the boxes from China. 



1. OUva lignaria, Marrat. 



Shell cylindrically oblong; spire depressed, callous; suture- 

 edge dotted; colour drab, with dark-brown interrupted 

 bands and angular lines, shaded with purplish spots and 

 dotted lines ; the whole interior of the aperture of a uniform 

 pui7)le brown; folds very prominent, one or two tinged 



