EAST COAST MARINE SHELLS 



103 



CAECUM CORONELLUIi Dall. Shell 

 thin, not much tapered; twenty- 

 four equal, only slightly raised, 

 threads; interspaces wider than 

 threads; the tube near adult aper- 

 ture suddenly enlarging in size; 

 plug hemispherical; mucro small; 

 surface glistening when perfect; 

 coronel- young shell with much flattened 

 lum, plug. Length 3.75-5.5 mm. Fig. 45. 

 Off North Carolina (14-18 

 fathoms); Egmont Key, 

 Florida 



Fig. 45 

 Caecum 



4 mm. 



CAECUM CAROLINIANUM Dall. When living cov- 

 ered with a thin yellov/ epidermis; white or 

 translucent underneath or streaked with 

 white; shell stout, thick arched; lines 

 very faint; aperture simple; posterior end 

 simple; plug conical, mucro formed by apex 

 of cone. Length 4.75 mm. 



Off North Carolina (15 fathoms); 

 Egmont Key, Florida 



CAECUM COO PER I S. Smith. About twenty- four 

 rounded longitudinal ribs crossed by numer- 

 ous rings, the latter not so distinct at 

 extremities of tube where ribs become obso- 

 lete. Plug mucronate v/ith apex inclining 

 to left; lateral profile concave; operculum 

 concave. Length 3.5 mm. 



The color is white, shell not very 

 thin, moderately curved. 



PI. 66, Fig. 8 



Vineyard Sound, Massachusetts to 



Florida 



CAECUM FLORIDANUM Stimpson. In the adult 

 stage it is recognizable by its comparative- 

 ly large size and numerous an- 

 nulations (those nearest the 

 aperture being most distant 

 and strongest); fine longitud- 

 inal striae, particularly be- 

 tween the rings. The plug has 

 a slender mucro, set to the 

 right and projecting from an 

 almost flat surface. Length 

 2 mm. 



This species lives in 

 shallow water and usually is 

 the most plentiful Caecum in "drift" on the 

 Florida beaches. Depth range 0-18 fathoms. 

 Fig. 46 

 North Carolina to Florida 



Fig. 46 

 Caecum florl- 

 danum, 2 mm. 



GENUS MEIOCERAS Carpenter 1858 



MEIOCERAS NITIDUM Stimpson. Shell minute, 

 shining, whitish or pale brown; swollen in 

 center, contracted near aperture; plug con- 

 vexly rounded; aperture concave. Length 

 2.5 mm. 



Tampa, Florida to V/est Indies; Palm 

 Beach, Florida; Newport, Rhode 

 Island 



Family Trichotropidae 



GENUS TRICHOTROPIS Broderip and 

 Sowerby 1829 



Shell thin, keeled, \imbilicated; 

 epidermis horny, extending like hairs at an- 

 gles of shell; operculum horny. 



TRICHOTROPIS BOREALIS COSTELLATUS Couthouy. 

 Whorls four, suture deeply channelled; sev- 

 eral rounded ribs or keels; mnbilicated. 

 Length about 18 mm. Epidermis shown in 

 Fig. 2. 



Damaged specimens are often taken 

 in the stomachs of fish. Depth 7-60 fathoms. 



PI. 55, Fig. 15 



Labrador to Massachusetts Bay 



Family Planaxidae 



Shell imperforate, spirally sul- 

 cate; epidermis thick; spire sharp; oval 

 aperture notched below; border of columel- 

 la with a ridge of tubercle above; opercu- 

 lum oval, paucispiral, nucleus almost termi- 

 nal. 



GENUS PLANAXIS Lamarck 1822 (FLAT AXIS) 



PLANAXIS LINEATUS Da Costa. Shell small, 

 solid, whorls a little convex; sculptured 

 with well-separated spiral grooves, most 

 conspicuous upon the upper portion of spire 

 and at base; outer lip heavy and slightly 

 deflected above; notch below rounded; color 

 yellowish or whitish with revolving brown 

 or whitish bands, sometimes entirely yellow 

 Length 7 man. 



This little shell is beautifully 

 variable in color ornamentation. The ground 

 color ranges from white to almost black and 

 the lines are often absent from the final 

 whorl. 



