MALACOZOA. GASTEROPODA. PECTINIBRANCHIATA. 53 



or angulate, the columella arcuate, and often a little 

 projecting. T/JQXOS, a potter's wheel, or a top. Lin- 

 naeus. 



1. Trdchus Sisyphmus. Shell imperf orate, conical, 

 acuminate, with the turns flat, spirally grooved, each 

 with a prominent rim on the angle, the upper turns 

 granulate. Named, I suppose, from some fancied ana- 

 logy to the rolling stone of Sisyphus ; if so, it is erro- 

 neously written zizyphinus, 



2. Trdchus conuloides. Shell imperforate, conical, 

 acute, with the turns flat, spirally grooved, with the 

 marginal ridge more prominent. Name from its re- 

 semblance to a cone. 



3. Trdchus Martini. Shell imperf orate, conical, 

 acuminate, with the turns flat, with cord-like ridges, 

 the angular margin of the turns with a very prominent 

 crenulated rim. Named by Mr. Smith after Major 

 Martin. 



4. Trdchus cmerdrius. Shell umbilicate, depressedly 

 conical, convex, of five sulcato-striate turns, of a pale- 

 grey colour, with radiating, undulated, reddish purple 

 lines. Cinerarius, ash-grey. 



5. Trdchus tumidus. Shell umbilicate convexo-conical, 

 of five turns, which are depressed above, sloping, striate, 

 brownish white, with transverse waved dusky or purple 

 lines. Tumidus y swelled or bulging. 



GENUS 2. PHORCUS. Shell roundish, rather depressed, 

 thickish, with the turns convex, the aperture circular, 

 subangulate anteriorly ; the umbilicus deep. Phdrcus, 

 according to Hesiod, a son of the sea and the earth. 

 Risso. 



1. Phdrcus Margarita. Shell roundish, rather de- 

 pressed, smooth, glossy, light-brown or olivaceous, with 

 the interior pearly. Margarita, a pearl. 



GENUS 3. SKENEA. Shell orbicular, discoid, with the 

 turns rounded, the aperture circular, the peristome com- 

 plete, the umbilicus wide. Named by Dr. Fleming after 

 l)r. Skene, an Aberdeen physician and naturalist. 

 E 2 



