264 MANUAL OF THE MOLLTJSCA. 



hooked, denticulated ; uncini about 70, gradually diminishing 

 outwards, hooked and denticulated. 



Distribution, 25 species. Australia, large species ; India, 

 Philippines, small species ; Mediterranean, Britain, West 

 Indies, very small species. 



Fossil, 70 species. Devonian (?). Europe. 



The similarity of the existing Australian fauna to that of the 

 European oolites strengthens the probability that some, at 

 least, of these fossil shells are rightly referred to Phasianella. 



Fig". 114.* 



Imperator, Montfoi-t. 

 Tj/pe, I. imperialis. PI. X., Fig. 4. 

 Synonym, Calcar. 



Shell trochiform, thick, with a flat or concave base ; whotls 

 keeled or stellated; aperture angulated outside, brilliantly 

 pearly ; operculum shelly. 



Distribution, 20 species? South Africa, India, Australia, 

 New Zealand. 



Trochus, L. 

 Etymology, trochus, a hoop. 



Synonyms, Cardinalia, Tegula, and Livona, Gray. Infundi- 

 bulum, Montfort. Chlorostoma, Sw. Trochiscus, Sby. Monilea, 

 Sw. 



Types, T. niloticus. PI. X., Fig. 5. T. ziz5T)liinus. Fig. 114. 

 Shell pyramidal, with nearly a flat base ; whorls numerous, 

 flat, variously striated ; aperture oblique, rhombic, 

 pearly inside; columella twisted, slightly trun- 

 cated ; outer lip thin ; operculum horny, multi- 

 spiral. Fig. 115 (T. pica). 



Animal with 2 small or obsolete head-lobes be- 

 tween the tentacles ; neck-lappets large ; sides 

 ^' ^^^' ornamented with lobes, and 3 — 5 cirri ; gill very 

 iong, linear; lingual teeth 11, denticulated; uncini — 90, 

 diminishing outwards- 



* Fig. 114. Trochus zizyphinus, L., Pegwell Bay, Kent. 



