MUSEUM OF COMPARATIVE ZOOLOGY. 65 



an ashy and another an olive tinge, but a fresh specimen is quite white. Lon. 

 of shell, 13.0 ; of last whorl, 8.0 ; of aperture, 5.25. Max. lat. 5.25 mm. Defl. 

 about 27°. 



Bed of the Gulf Stream, Pourtales, 447 fms. Station 19, 310 fms. Station 

 43, 339 fms. Sigsbee, off Havana, 450 fms. Station 2, 805 fms. 



P. (Drillia) detecta n. s. 



Shell having a strong superficial resemblance to the last, but with a totally 

 different nucleus, and with differences in details of sculpture ; it also has not 

 the minute punctation ; color white or ashy gray ; nucleus and nuclear whorls 

 heliciform, with a sculpture of slightly raised lamellae waved backward from 

 the middle point of the periphery both ways ; under these are also fine revolv- 

 ing raised lines ; whorls in all nine ; remainder with a transverse sculpture of 

 from sixteen to (on the last whorl) eighteen narrow raised riblets passing en- 

 tirely over the whorls, quite faint on the band and only obsolete on the 

 columella and canal ; beside these the lines of growth are unusually distinct, 

 somewhat raised and rounded, and are especially well marked on the notch- 

 band ; revolving sculpture consisting of three or four (on the last whorl thir- 

 teen) raised rounded threads slightly swollen where they cross the transverse 

 riblets ; between these are usually two, but sometimes as many as four, similar 

 but finer threads, which also invade the band and cover the pillar, but cross 

 the riblets without enlarging ; the interspaces between the ribs are less deep, 

 and the whole sculpture more uniform and less prominent than in the last 

 species ; suture appressed ; band less prominent than in the last ; notch 

 shallow, pillar nearly straight, canal very slightly recurved ; outer lip (not 

 adult) thin. Lon. of shell, 11.75 ; of last whorl, 6.75 ; of aperture, 4.5. Max. 

 lat. 4.5 mm. Defl. about 27°. 



Station 43, 339 fms. 



In the absence of any perfectly mature specimen it is impossible to say what 

 the mouth characters would be, but it seems likely that they would resemble 

 the last species from the general similarity of the juvenile portion. 



P. (Drillia) serga n. s. 



Shell small, dull, slender, yellowish white, eight-whorled ; nucleus small, 

 translucent, shining, passing into the sculpture of the adult gradually, in two 

 and a half nuclear whorls, which show first minute transverse wrinkles on the 

 periphery of the second whorl ; succeeding whorls transversely Bculptured by 

 eight to twelve slightly oblique angular riblets, which pass entirely over the 

 whorls, and only become obsolete on the canal ; these are crossed, fust by (on 

 the upper whorls) two or (on the last whorl) nine rounded threads which rise 

 to sharp points on reaching the summits of the riblets, and are perfectly dis- 

 tinct in the interspaces ; secondly, by finer intercalary revolving threads, which 

 pass without change over the riblets, usually to the number of three or four 

 between each pair of primary threads ; these also cover the notch-band, and 



vol. ix. — no. 2. 5 



