11.4 THE VOYAGE OF H.M.S. CHALLENGER. 



central area traversed by longitudinal opaque brown bands (PI. XII. fig. 9). The 

 clear edge (iv.c), usually so abundantly provided with spicules and forming such a 

 favourable locality for observing them on account of its transparency, exhibits no trace of 

 them whatever. It is on each side fully a quarter of the total breadth of the organ, and 

 is covered with squamous epithelium. The edge is bounded internally by an opaque 

 brown band (l.b.b.) of moderate breadth. This, the lateral band, is separated from the 

 central brown area by a clear space of moderate breadth. The central area (c.b.a.) has a 

 median broad dark brown band running down the centre and in places traversed by a 

 central fine clear line. This broad band is separated by a narrow clear space from a 

 narrow very dark brown band on each side. These narrow bands bounding the central 

 area, are a little irregular in their course. 



The Dorsal Lamina is represented as usual by a series of languets. They are 

 triangular in form, rather wide at the base and tapering to a point. They are rather 

 closely placed. 



The Tentacles are numerous. A few of them are much larger than the others, being 

 of considerable size, and are much branched (PL XII. fig. 10, tn.). The remainder 

 are all much smaller, but are of various sizes (tn/ tn"), and have apparently no definite 

 arrangement. 



The Dorsal Tubercle lies near the posterior end of the large and very irregular peri- 

 tubercular area (PI. XL fig. 12). It has the form of a short sugar doaf, the base or 

 open (?) end being posterior and turned towards the right side, while the pointed end is 

 directed anteriorly and to the left, and seems to be in direct connection with the anterior 

 extremity of the nervous mass. The peritubercular area is large and wide ; its breadth 

 at the mouth is fully greater than its depth. 



The Peripharyngeal Bands are narrow but distinct. Where they bound the sides of 

 the peritubercular area they have a very irregular course (PL XL fig. 12, p.p.), undulating 

 and forming sharp folds, so as to give the generally triangular peritubercular area a very 

 complicated outline. 



TJie Nerve Ganglion lies at the apex of the peritubercular area (PL XL fig. 12, n.g.). 

 It is much shorter than in Culeolus recumbens and has an oblong form, narrowed slightly 

 towards the ends. The posterior extremity splits into two large nerve trunks, while the 

 anterior is hidden in the pointed extremity of the dorsal tubercle. 



The Alimentary Canal lies on the left side of the branchial sac. The oesophagus is 

 very short and passes over imperceptibly into the large stomach (PL XL fig. 13, st.), 

 which is a long irregularly fusiform body with no cajcal processes as in Culeolus 

 murrayi and Culeolus recumbens. The intestine, after emerging from the stomach, 

 continues its direction for a short distance, and then turns in a wide loop and 

 runs back parallel to the stomach, with the edge of which it is in connection, 

 passes close to the oesophageal aperture, and, curving up dorsally, ends close to the 



