GLOSSOBALANUS MARGINATUS 581 



helps to define them. Ventrally on the trunk the brown 

 pigment is concentrated to form a paired series of dark spots 

 which he one on each side of the ventral median line. 



The proboscis is short and rounded, laterally compressed 

 in front and expanded on each side near the collar. At this 

 point it measures transversely 5 mm. It narrows again 

 rapidly to form a neck of attachment to the collar, which 

 provides a recess for its reception. The neck dorsally 

 presents a single median proboscis pore. Behind the pore 

 an opening on the anterior wall of the collar may be artificial, 

 but it is in the position of the neuropore (Text-fig. 3). The 

 proboscis was cut in two transversely before the specimen 

 reached me. The interior is a wide cavity which, as has 

 been said, communicates with the exterior by a median 

 proboscis pore. Basally it presents a simple diverticulum 

 or so-called notochord, and there is no vermiform process. 



The collar is markedly muscular. It forms a folded edge 

 anteriorly, and it is occupied around the middle of its length 

 by a groove. It is rounded in section and the groove 

 measures about 5 mm. in all diameters. The collar is also 

 defined posteriorly by an edge, but passes after a slight 

 depression into the trunk. 



The trunk is resolved externally into the ventral body-wall 

 and the genital wings, and these are separated by a lateral 

 groove which, like the genital wing at first gradually and 

 posteriorly more rapidly, is carried towards the dorsal aspect 

 of the body (Text-fig. 1). The wings are occupied by the 

 gonads in the form of irregularly folded but on the whole 

 transverse ridges which project from the surface. They are 

 large and in the specimen approximated over the dorsal 

 region of the body so as to occlude the latter from the 

 exterior. 



The genital wing of the left side is larger transversely than 

 that of the right, and this mark of asymmetry is emphasized 

 by the sinuous path of longitudinal features of structure 

 like the dorsal groove between the genital wings, the ventral 

 nerve-cord, and the paired series of pigment spots. The 



