CADULUS-GADILA. 175 



treadth at mouth 0'015, at swelling 0'023, at apex O'Ol inch. (Wat- 

 son). 



Lat. 18 38' 30" N., long. 65 5' 30" W., Culebra Island, West 

 Indies, 390 fms. (Challenger). 



C. rastridens WATSON, Journ. Linn. Soc. Lond., Vol. xiv, p. 525 

 {1879) ; Chall. Keport, Scaphopoda, p. 19, pi. 3, fig. 3 (1885). 



C. CURTUS Watson. PI. 25, fig. 60. 



Shell short, broad, narrowed at both ends, scarcely bent, and that 

 almost wholly near the mouth : swollen in the middle, so as to bulge 

 a little on the concave curve. Though the mouth is larger than the 

 apex, the whole shell is a little more pinched in front than behind, 

 and is very slightly laterally compressed (in the proportion of about 

 14 to 15). It is thin, polished, translucent white, with one, some- 

 times two opaque rings near the apex. Sculpture: Only under a 

 high power of the microscope can some very close transverse strise 

 be seen in the texture of the shell. Mouth rather large, very 

 slightly oblique ; edge thin and generally much chipped ; apical 

 opening small, straight, chipped. The opaque rings result from 

 thickening, caused by a thin projection which narrows the opening. 

 Length O'l inch, breadth at mouth 0'019, greatest 0'03, apex 0.012 

 inch. (Watson). 



Lat. 18 38' 30" N., long. 65 5' 30" W., Culebra Island, West 

 Indies, 390 fms. (Challenger). 



C. curtus WATSON, Journ. Linn. Soc. Lond., xiv, p. 527 (1879) ; 

 Chall. Report, Scapbopoda, p. 21, pi. iii, fig. 7. 



Than C. curtus var. congruens Wats., this is not only very much 

 smaller, but here the mouth is oblique, and the shell is straighter 

 behind and more bent in front, where, too, it is much more pinched 

 in. It is nearly of the same length as C. obesus Wats., but is very 

 much narrower. ( Wats.). 



Var. CONGRUENS Watson. PI. 25, fig. 59. 



This differs from Cadulus curtus Wats., in being one-third larger, 

 the mouth is, perhaps, less oblique, but being in both specimens 

 much chipped, this may be accidental. The most remarkable feat- 

 ure of difference is that it is perfectly round, and not like the other, 

 laterally compressed ; I attribute this difference to age. At all 



