1904.] NATURAL SCIENCES OF PHILADELPHIA. 175 



inclined forwarcV and inward. The last two especially have their 

 ventral ends entirely free, and those of the last meet in the middle line. 

 The ventral plates, which are included in the area between the tori, 

 consequently form a nearly equilateral triangle with the apex caudad. 

 All of the abdominal somites are short and crowded, especially poste- 

 riorly, and no caudal plate or membrane is developed. The anus is 

 terminal. No pigment remains in the specimen. 



Somite I bears a compact slender tuft of pale, ghstening, lanceolate, 

 limbate setse. They differ considerably in length, width of wing and 

 curvature, but all have the margins very distinctly serrated. On the 

 other thoracic somites the setse are of the same form, but the wings 

 are generally shorter and broader, the bmidles less compact and more 

 spreading, and more distinctly arranged in tw^o rows, one of larger, 

 the other of smaller setse. Abdominal somites generally bear three 

 delicate colorless setae of the form shown in fig. 36. They are appa- 

 rently not trumpet-shaped, but spatulate, with one angle of the flat- 

 tened end prolonged obliquely into a conspicuous spine upon which 

 the dehcate teeth are continued. The stems are delicately longitudi- 

 nally striated. The posterior abdominal sette are all broken off. 



The thoracic uncinigerous lines begin at the seta tufts and are rather 

 long, that of somite II containing a few more than 200 uncini, which 

 decrease in size toward the ventral end. Abdominal tori contain 

 little more than | as many. The uncini are delicate pectinate plates. 

 Those of the thoracic somites (fig. 37) have quadrate plates bearing 

 13-15 strongly decurved, very acute teeth; the lowermost scoop-tooth 

 is broad, opens toward the uncinial plate and projects freely beyond 

 the lower margin of the latter. Abdominal uncini (fig. 20) are about 

 •i as large and have only 11 or 12 acute teeth besides the scoop-like 

 one, and the plate is triangular, with its lowermost angle produced into 

 a process about j as long as the lowermost tooth. 



Suruga Bay, 3,713, 45 fms., type only, without tube. 



The Spirorbes in the collection w^ere submitted for study to Miss 

 Katharine J. Bush, of the Yale University Museum, who has kindly 

 furnished the following descriptions: 

 Spirorbis argutas Bush sp. nov. 



Tube coiled in a low discoid sinistral form with large central cavity, 

 spreading around the base in a thin layer, the whorls radially enlarging 

 and ornamented by one large median keel which renders the surface 

 on each side slightly concave, all crossed by distinct transverse lines. 

 Smaller specimen about 1 mm. in diameter; larger^ about 1.5 mm. 



