148 CADULUS-POLYSCHIDES. 



a'". Large, strongly swollen close to the oblique, markedly- 

 contracted and oval aperture ; a moderately deep apical 

 notch on each side and smaller ones above and below ; 

 length 22 mill., bh times the greatest diameter, 



spectabilis, p. 153. 



III. Moderately inflated anteriorly ; apex with a deeper notch on 



each side, the margin along convex side subdivided into 2, that 



along concave side into 3 rounded teeth; length 11-14 mill., 



about 52 times the greatest diam. Off west coast Patagonia, 



(lain, p. 155. 



C. TETRASCHisTus (Watson). PI. 23, fig. 1. 



Shell cylindrical, tapering, bent and attenuated from about the 

 middle to the apex ; toward the mouth very slightly contracted, ft 

 is rather strong, and has the dull gloss and white translucency of a 

 quill. There are two opaque bands round the apex. 



Sculpture : There are traces, exceedingly faint, of fine close-set 

 strise, which run elliptically round the shell on the lines of growth, 

 and in some lights there is just a reflection as of some sort of remote 

 longitudinal texture (very like that in Siphodentalium (Dischides) 

 bijissum Wood). The edge of the mouth slopes backward very 

 obliquely from the concave to the convex side of the shell; it is 

 thick, and all round it is smoothly rounded off". The apex projects 

 on the convex side of the shell, and is split by four opposite, shal- 

 low, unequal, irregular, rough-edged, gaping clefts, so arranged as ta 

 leave the teeth at the convex and concave curves and at the two 

 sides. The bands round the apex are two narrow, callus-like inter- 

 nal ribs. Length, 0'298 inch ; breadth at mouth, 003 ; at broadest^ 

 0-035; at apex, O'OIT inch (Watson). 



Anchorage off Fernando Noronha, 25 fms. (Challenger). 



Siphodentalium tetraschistnm Watson, Journ. Linn. Soc. Lond., 

 xiv, p. 521 (1879) ; Chall. Rep., p. 15, pi. 2, f. 8. 



Siphonodentalium quadridenfatum Dall, Bull. Mus. Comp. Zool., 

 ix, p. 36 (July, 1881). — Cadulus quadridentatns Dall, Blake Gas- 

 tropoda, p. 428, pi. 27, f 5 (1889) ; Trans. Wagner Inst. Sci., iii, p. 

 445 (1892) ; Bull. U. S. Nat. Mus., No. 37, p. 76, pi. 41, f 20 (1889); 

 Proc. U. S. Nat. Mus., xii, p. 295. — C. incisus Bush, Trans. Conn. 

 Acad. Sci., vi, p. 471, pi. 45, f 20 (June, 1885). 



C tetraschistus is the senior or earliest-described member of a 

 group of closely allied forms having similar -l-cleft apices, from the 



