304 SPECIES OF THE SYSTEMA. 
of the Natica collaria of Lamarck, but that species is too briefly 
defined for me to absolutely assert the identity. Since I cannot 
indicate any other species to which I could unhesitatingly refer 
it, I have thought it advisable to describe the Linnean ex- 
amples, premising that I have seen specimens that only differ 
in the rich brown hue of their pillar-lip, which colouring fades 
upon exposure, so as to suit the language of the ‘Museum 
Ulrice :’ it is likely enough, however, that the specimen from 
which the later account in that publication was drawn up was 
essentially distinct, as in many other instances, from the indi- 
viduals so briefly, characterised in the ‘ Systema.’ 
Shell subglobose, rather depressed, broader than long, solid, 
smooth, not particularly glossy ; surface almost entirely painted 
with a kind of network or close venulation of crowded, angularly 
flexuous, livid or reddish brown lines, that expose at irregular 
intervals numerous sagittate, whitish markings (these in the 
Linnean specimens are arranged in a somewhat spiral fashion, 
with their points leaning in the same direction), which seem 
generally more abundant along a narrow strip that runs a little 
below the middle of the body-whorl, and thus forms an in- 
distinct fillet. The lines, being coarser and more distant 
below the tolerably distinct suture, appear to diverge from it on 
a whitish band, more particularly on the smaller turns which 
are elsewhere of an uniform livid hue. Whorls moderately 
convex, rather narrow; spire decidedly short and obtuse. 
Mouth rather narrow, filling two-thirds of the total length; 
throat of the adult usually stained with purple; inner lip 
whitish. Umbilical region dark rufous brown, girt with a more 
or less distinct white band; perforation commencing nearly half 
way up the shell, simple, contracted by a gibbous projection of 
the middle of the solid pillar-lip. Length five-sixths of an 
inch, Gibraltar and Algeria. 
Mervita httellus. 
Linneus has quoted a very recognisable delineation (Rumph. 
pl. 22, f. D) of the Natica rufa of authors as his sole illustration 
of this Nerite, and as the extremely brief diagnosis appears, to 
me at least, to apply fairly to that shell, the species may be 
