SCISSURELLA. 283 



Genus SCISSUREL'LA*, D'Orbigny. PL VII. f. 2. 



SHELL having a more or less depressed spire, and an open slit 

 in the outer lip which is closed behind in the course of growth. 



In the ' Zoological Journal' for June 1824, Mr. G. B. 

 Sowerby suggested the possibility of this " proving to 

 be either an Haliotis or a Fissurella, just emerged from 

 the egg ; " he supposed that the slit or notch existed 

 only in young specimens. He was apparently led to 

 form this strange conception by having mistaken for 

 adult Scissurella shells belonging to the genus lately 

 described by me as Schismope, which have an orifice 

 behind the front margin, instead of an open slit at the 

 edge. D'Orbigny especially notices this open slit as a 

 generic character of Scissurella', and he compares it 

 with that of Pleurotoma, Emarginula, and Siliquaria, 

 placing Scissurella among his Trochoidea. Some con- 

 chologists have referred the present genus to Anatomus 

 of De Montfort; but his description and illustrative 

 figure (the latter copied from Soldani) show a flat-spired 

 or discoidal shell, having a circular mouth with a slit on 

 the lower side certainly not the position of the slit in 

 Scissurella. He evidently considered his Anatomus one 

 of the Polythalamous or chambered Foraminifera, and 

 he associated with it the fry of some mollusk which he 

 found adhering to the " Sargasso " or Gulf- weed. I 

 am therefore not inclined to substitute Anatomus for 

 Scissurella. 



N?2i SCISSURELLA CRISPA'TA f, Fleming. 



S. crispata, Flem. Mem. Wern. Soc. vi. p. 385, pi. 6. f. 3 ; F. & H. ii. 

 p. 644, pi. kiii. f. 6. 



BODY greyish-white: head prominent, with the mouth 

 * From a small slit in the shell. t Curled. 



