158 ONYX AND DIPELTIS. 



as the latter is behind the head ; it is two-thirds as wide as the 

 body and fully twice as long as wide, and inasmuch as the poms 

 is situated just behind the mouth (-7) empties its excretion 

 through an unusually long duct. This duct ends in a distinct 

 ampulla, which is connected with the exterior by the usual 

 chitinous tube, here, however, of unusually great length. 



-6 ?) i'-4 T-5 "*2-" (?> 9 i'6 2 ' mm> ^is formula is based on the measure- 

 ments of a single adult male. The tail is more strongly arcuate 

 than that of the female. There are apparently two testicles arranged 

 symmetrically, the anterior end of the foremost lying near the 

 middle of the body. The ductus ejaculatorius is one-fourth as wide 

 as the body, and is composed of two rows of cells. The two equal, 

 strongly arcuate, linear, acute spicula compass an arc of 180°. 

 Their proximse are hardly cephaloid. They are somewhat longer 

 than the anal diameter, and are supported in action by a single 

 accessory piece one-half as long and furnished with a backward- 

 pointing process. 



Hab. Coral-bank, Secca della Gajola, Bay of Naples, at a depth 

 of thirty-five metres. 



