96 SCALAR! I D.E. 



Belgian Crag formations^ is closely allied to it^ if not 

 the same sliell. 



4. S. clathra'tula"^, Adams. 



Turbo clathraMus, Ad. Micr. t. 14. f. 19. 8. clathratula, F. & H, iii. 

 p. 209, pi. Ixx. f. 3, 4. 



Body clear- white, with a very faint dusky tinge on the 

 upper part, and thickly interspersed with minute opaque- 

 white flakes : mantle fleshy, even with the mouth of the shell : 

 snout very short, compressed and crescent-shaped : prohoscis 

 long and strong, frequently protruded : tentacles of moderate 

 length, and divergent : eyes very black, placed not on ofl'sets, 

 but on scarcely raised eminences at the outer bases of the ten- 

 tacles, of which they form part : foot often carried considerably 

 in advance of the head and tentacles ; it is short, narrow, 

 in front nearly semicircular and with a minute auricle at each 

 corner, and tapers gradually behind to a slender rounded termi- 

 nation ; hinder half of the sole deeply grooved in the middle 

 lengthwise, with a depression in the centre. (Clark and Alder.) 



Shell elegantly pyramidal, rather tliin, semitransparent, 

 and glossy: sculpture, flne, sharp, laminar, erect, and curved 

 longitudinal ridges, set rather obliquely, either in a continuous 

 or alternate order ; each is nearly of the same height and size 

 throughout, and very seldom are any of them varicose ; there 

 are 18 on each of the last two whorls, and 16 or 17 on the 

 next, diminishing in number upwards ; their interstices are 

 spirally but indistinctly and irregidarly striated, as in the other 

 species, and on the upper part of the body-whorl some fine 

 longitudinal striae may occasionally be observed ; the first 3 

 or 4 whorls are smooth and polished : colour uniform, snow- 

 white : sjyire finely tapering ; apex like that of the other species : 

 whorls 12-13, convex, gradually enlarging : suture deep : 

 mouth inclining to oval, decidedly angulated below: outer lip 

 incurved above, and slightly expanding : inner lip reflected, 

 especially at the base : operculum yellowish-brown, having 

 from 4 to 5 turns, concave in the middle, and marked with 

 strong flexuous striae in the line of growth, L. 0-6. B. 0-02. 



Habitat : Sparingly distributed throughout all our 

 seas, from the Shetland to the Channel Isles. It pro- 



* Small-barred : diminutive of clathrata, from the Linnean specific 

 name clathrus. 



