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



and divided into an outer broad lighter, and an inner narrow darker band formed of 

 closely packed columnar cells (PI. XII. fig. 5). Between the two opaque brown areas 

 lies the central fifth, which is semi-transparent but darker than the raised edge. Neither 

 the opaque brown areas nor the central clearer part contain spicules. 



The Dorsal Lamina is replaced by a series of large triangular languets. They are 

 not broad at the base, and taper gradually to a blunt point. They are moderately 

 closely placed, there being about two to each mesh — one opposite each transverse vessel 

 and one between each pair. 



Tlie Tentacles are branched and are very long. There are about twenty-four of them, 

 and they are of two sizes, placed alternately. They are more branched and larger in 

 comparison to the size of the body than in either of the preceding species. One of 

 the ordinary large tentacles measures about 9 mm. in length. Ramifying calcareous 

 spicules are present here and there, but they are not at all numerous. 



TJie Dorsal Tubercle is of small size and is ellipsoidal in form, having no aperture, 

 and consequently no horns (PI. XL fig. 6, d.t.). It lies near the posterior angle of the 

 large triangular peritubercular area, and is immediately below the nerve ganglion, being- 

 situated at the right side of its anterior end. 



The peritubercular area is large and of an irregularly triangular form. It is not, 

 however, very deep, being broad at the anterior end. The peripharyngeal bands are 

 narrow and undulated. As in the last species the band extends further forwards on 

 the left side of the peritubercular area than on the right (PL XL fig. 6, p.p.). 



The Nerve Ganglion is of considerable size, and much elongated antero-posteriorly. 

 It is narrow and of much the same calibre throughout, swelling slightly in its atrial half. 

 It lies with its middle point placed about the apex of the peritubercular area (PI. XL 

 fig. 6). The branchial end divides into two divergent nerves (br.n.), at the origin of one 

 of which (the right) the dorsal tubercle is situated. The atrial end of the ganglion gives 

 off four nerve trunks, two ]30steriorly side by side (at.n.) and two laterally at right angles 

 to the axis of the sano-lion, one to each side. The left one soon subdivides into two 

 branches. 



The Alimentary Canal. — The oesophageal opening (PL XL fig. 7, a?.) is at the posterior 

 end of the branchial sac, and the oesophagus is a short round tube running ventrally and 

 anteriorly to enter the large stomach (st.) which lies along the left side of the ventral edge 

 of the branchial sac. Like the stomach in Culeolus murrayi it is very irregular. It has 

 three prominent lobes or pouches, each of which ends in a large number of small papilla-like 

 processes. The intestine emerges from the anterior narrower end of the stomach, and 

 continues its direction forwards on the left side of the branchial sac, and then curves 

 round in a wide loop dorsally, and runs posteriorly as far as the level of the intestinal 

 end of the stomach, and there ends in the anus («.) which has its margin cut into a 

 papillary fringe. 



